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This study provides the first descriptions of sperm storage at the tissue and cellular levels in a female frog or toad. Oviducal anatomy was studied by light and electron microscopy in Ascaphus truei from north coastal California. Ascaphus truei is one of the few species of anurans in which fertilization is internal. Unlike other anurans with inter...
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... terminology, except where noted, follows Sever et al. (1996a) and Wake and Dickie (1998). Regions of the oviduct of Ascaphus truei are illus- trated in Figures 1 and 2. The ostial opening leads into the infundibulum, which is a narrow, thin- walled tube that extends from posterior to the trans- verse septum to the anterior border of the kidney. ...
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... the "uterus" by Metter (1964b). In the anterior por- tion of the ovisac are exocrine glands that serve as sperm storage tubules (SSTs). The ampulla and the ovisac are the only regions of the oviduct that pos- sess intrinsic tubular exocrine glands (Fig. 2). The two ovisacs join medially dorsal to the urinary blad- der to form an oviducal sinus (Fig. 1). The only other anuran in which an oviducal sinus has been noted is the viviparous African bufonid Nimbaphrynoides oc- cidentalis by Xavier (1973). This area is clearly an- terior to the cloaca, which is dorsal to the pubic symphysis. The oviducal sinus is not "urogenital," because the Wolffian ducts and urinary bladder empty into the ...
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... a dense submesothelial layer of collagen fibers (Fig. 3B). The middle muscularis layer is thin in the infundibulum and is composed primarily of longitudinal smooth muscle fibers. Else- where in the oviduct both a superficial circular and a deep longitudinal layer are apparent, with these most prominent in the ovisac (Fig. 5A) and oviducal sinus (Fig. 12A). The deepest layer is the mucosa, composed of the epithelium lining the inner walls of the oviduct and the subsurface connective tissue of the lamina propria. The mucosa, especially the epi- thelium and intrinsic exocrine glands derived from the epithelium, shows the most variation through- out the oviduct and is the focus of the ...
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... Sperm occur in the oviducal lumen and the SSTs of the anterior ovisac (Figs. 10, 11) of the nonvitellogenic females examined from June and July (Table 1). Sperm are especially numerous and closely packed in the SSTs and clusters of sperm often exhibit the same orientation of their axes (Fig. 10B-D, 11A). Occasional sperm nuclei are embed- ded in the apical cytoplasm of SSTs and these sperm, like those in the lumen, ...
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... Sperm occur in the oviducal lumen and the SSTs of the anterior ovisac (Figs. 10, 11) of the nonvitellogenic females examined from June and July (Table 1). Sperm are especially numerous and closely packed in the SSTs and clusters of sperm often exhibit the same orientation of their axes (Fig. 10B-D, 11A). Occasional sperm nuclei are embed- ded in the apical cytoplasm of SSTs and these sperm, like those in the lumen, appear normal in cytology (Fig. 11B). No evidence for spermiophagy was observed. Ciliated cells were numerous. Many secretory cells lack extensive clusters of secretory vacuoles, but other cells contain numerous, electron- ...
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... females examined from June and July (Table 1). Sperm are especially numerous and closely packed in the SSTs and clusters of sperm often exhibit the same orientation of their axes (Fig. 10B-D, 11A). Occasional sperm nuclei are embed- ded in the apical cytoplasm of SSTs and these sperm, like those in the lumen, appear normal in cytology (Fig. 11B). No evidence for spermiophagy was observed. Ciliated cells were numerous. Many secretory cells lack extensive clusters of secretory vacuoles, but other cells contain numerous, electron- dense, PAS secretory vacuoles (Fig. 11A,C). Vacu- oles with a lighter density as noted in females with large ovarian follicles (Figs. 5D, 6D) are ...
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... nuclei are embed- ded in the apical cytoplasm of SSTs and these sperm, like those in the lumen, appear normal in cytology (Fig. 11B). No evidence for spermiophagy was observed. Ciliated cells were numerous. Many secretory cells lack extensive clusters of secretory vacuoles, but other cells contain numerous, electron- dense, PAS secretory vacuoles (Fig. 11A,C). Vacu- oles with a lighter density as noted in females with large ovarian follicles (Figs. 5D, 6D) are lacking. Occasional lipid droplets (Fig. 11B,C) occur in the cytoplasm of secretory cells and these lipids stain Sudan Black in frozen sections. Capillaries closely abut the basal lamina (Figs. 10B, 11A). In some secretory cells that ...
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... was observed. Ciliated cells were numerous. Many secretory cells lack extensive clusters of secretory vacuoles, but other cells contain numerous, electron- dense, PAS secretory vacuoles (Fig. 11A,C). Vacu- oles with a lighter density as noted in females with large ovarian follicles (Figs. 5D, 6D) are lacking. Occasional lipid droplets (Fig. 11B,C) occur in the cytoplasm of secretory cells and these lipids stain Sudan Black in frozen sections. Capillaries closely abut the basal lamina (Figs. 10B, 11A). In some secretory cells that lack large vacuoles, mitochon- dria and Golgi complexes are prominent in the pe- rinuclear cytoplasm (Fig. ...
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... electron- dense, PAS secretory vacuoles (Fig. 11A,C). Vacu- oles with a lighter density as noted in females with large ovarian follicles (Figs. 5D, 6D) are lacking. Occasional lipid droplets (Fig. 11B,C) occur in the cytoplasm of secretory cells and these lipids stain Sudan Black in frozen sections. Capillaries closely abut the basal lamina (Figs. 10B, 11A). In some secretory cells that lack large vacuoles, mitochon- dria and Golgi complexes are prominent in the pe- rinuclear cytoplasm (Fig. ...
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... 5D, 6D) are lacking. Occasional lipid droplets (Fig. 11B,C) occur in the cytoplasm of secretory cells and these lipids stain Sudan Black in frozen sections. Capillaries closely abut the basal lamina (Figs. 10B, 11A). In some secretory cells that lack large vacuoles, mitochon- dria and Golgi complexes are prominent in the pe- rinuclear cytoplasm (Fig. ...
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... sinus. The epithelial lining of the ovid- ucal sinus in females with small ovarian follicles (Fig. 12) is similar to that of the vitellogenic female that was not sacrificed while in copulexus (Fig. 7). Most cells bordering the oviducal lumen are filled with large secretory vacuoles. In females with small ovarian follicles, however, these vacuoles are of varying densities rather than the more uniform den- sities observed in females with ...
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... 7). Most cells bordering the oviducal lumen are filled with large secretory vacuoles. In females with small ovarian follicles, however, these vacuoles are of varying densities rather than the more uniform den- sities observed in females with large ovarian folli- cles. Interdigitations and junctions between adja- cent epithelial cells are complex (Fig. 12B,C). Some apical cells lack secretory vacuoles and contain nu- merous mitochondria with tubular cristae (Fig. ...
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... follicles, however, these vacuoles are of varying densities rather than the more uniform den- sities observed in females with large ovarian folli- cles. Interdigitations and junctions between adja- cent epithelial cells are complex (Fig. 12B,C). Some apical cells lack secretory vacuoles and contain nu- merous mitochondria with tubular cristae (Fig. ...
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... extant representatives of Actinistia and Dip- noi, descendant taxa of sarcopterygiian sister groups of amphibians (Schultze, 1994), possess oviducts (Millot and Anthony, 1960;Wake, 1987) and Latim- eria is viviparous ( Smith et al., 1975), indicating that fertilization is internal (Fig. 13). Sperm stor-age, however, has not been reported in Latimeria or any of the extant ...
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... Lissamphibia is generally considered mono- phyletic and consists of three groups, the Anura, Caudata, and Apoda. Most evidence supports a frog salamander clade ( Pough et al., 1998) (Fig. 13). Sperm storage is unknown in female apodans, even though internal fertilization apparently occurs in all taxa, and many caecilians are viviparous (Wilkinson and Nussbaum, 1998). Aside from Asca- phus, only a few anurans have internal fertilization, with sperm transfer accomplished by cloacal appo- sition. These species include ...
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... research needs to be done to determine whether oviducal sperm storage occurs in caecilians and internal-fertilizing bufonids and leptodactylids. Ascaphus truei, however, is not the sister taxon of any caecilian or of the other internal-fertilizing frogs (Fig. 13), so oviducal sperm storage must be consid- ered independently derived in A. ...
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... some forms the sperm are in orderly arrays in the spermathecae (Sever and Hamlett, 1998), whereas in others sperm are in tangled masses ). Alignment of sperm may depend to some degree on the anatomy of the spermatheca (more orderly in compound glands than simple tu- Fig. 13. "Scenariogram" (see Wake and Larson, 1987) showing distribution of internal fertilization and sperm storage in the Lissamphibia and extant sarcopterygiians (descendant taxa of piscine ancestors to amphibians). Only relevant and otherwise most inclusive taxa are shown. Two of the four species of Necto- phrynoides reported by Wake ...
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This study provides the first descriptions of sperm storage at the tissue and cellular levels in a female frog or toad. Oviducal anatomy was studied by light and electron microscopy in Ascaphus truei from north coastal California. Ascaphus truei is one of the few species of anurans in which fertilization is internal. Unlike other anurans with inter...
Citations
... Sperm storage, as a survival strategy beneficial for a variety of animals, including insects, fish, amphibians, reptiles, birds, and mammals, occurs in the female reproductive tract (Holt and Lloyd 2010; Holt 2011). To achieve fertilization, the sperm migrate within the female reproductive tract to encounter the oocytes (Sever et al. 2001). However, there is a discrepancy in the timing of ovulation in the female and the time of insemination by the male (Neubaum and Wolfner 1998; Suarez 2008b). ...
The initiation of innate immunology system could play an important role in the aspect of protection for sperms long-term storage when the sperms got into oviduct of turtles and come into contact with epithelium. The exploration of TLR2/4 distribution and expression in oviduct during hibernation could help make the storage mechanism understandable. The objective of this study was to examine the gene and protein expression profiles in Chinese soft-shelled turtle during hibernation from November to April in the next year. The protein distribution of TLR2/4 was investigated in the magnum, isthmus, uterus, and vagina of the turtle oviduct using immunohistochemistry, and the gene expression of TLR2/4 was analyzed using quantitative real-time PCR (qRT-PCR). The results showed positive TLR2 protein expression primarily in the epithelium of the oviduct. TLR4 immunoreactivity was widely observed in almost every part of the oviduct, particularly in the epithelium and secretory gland membrane. Analysis of protein, mRNA expression revealed the decreased expression of TLR2/4 in the magnum compared with the isthmus, uterus, and vagina during hibernation. The protein and mRNA expression of TLR2 in the magnum, isthmus, uterus, and vagina was decreased in April compared with that in November. TLR4 protein and mRNA expression in the magnum, isthmus, uterus and vagina was decreased in November compared with that in April. These results indicated that TLR2/4 expression might protect the sperm from microbial infections. In contrast to the function of TLR2, which protects sperm during the early stages of hibernation, TLR4 might play a role in later stages of storage. The present study is the first to report the functions of TLR2/4 in reptiles.
... The unique life history of tailed frogs can result in temporal overlap between the first two periods because of individual and life stage variation. Both species of tailed frogs engage in internal fertilization that involves sperm storage for relatively long intervals (months to perhaps years; A. truei: Noble 1925, Noble and Putnam 1931, Sever et al. 2001; and A. montanus: Metter 1964b). Unlike other frogs in the PNW and elsewhere, this results in the temporal separation of breeding (coupling of adults) and oviposition (the laying of eggs; Brown 1975), a phenomenon that Jameson (1955) first pointed out. ...
... ). However, on the North Fork of the Mad River in northern California, mating is claimed to have been observed only in May, though males with secondary sexual characteristics have been observed in June and July (Sever et al. 2001); the seasonal effort that this assessment is based on is unclear. A few additional breeding observations exist for A. truei in March–May, but these involve individuals introduced into the same container following capture. ...
... Noble made key contributions through his discoveries of sperm in female oviducts, concealed cloacal spines that become visible as blood fills the breeding male "tail", and male ability to direct their "tail" forward and insert it into the female cloaca (Noble 1925, Noble and Putnam 1931). Of the over 6,400 currently recognized species of anurans, A. truei is the only species known to engage in copulation that includes intromission (Sever et al. 2001). In fact, coupling in A. truei has been termed copulexus due to the distinctive combination of amplexus with internal fertilization using the "penis-like" cloacal tail (Sever et al. 2001). ...
Tailed frogs comprise the only two living species in the genus Ascaphus, a group of frogs endemic to the Pacific Northwest (PNW) of North America. As the sister group of all other living frog species, tailed frogs have a unique array of primitive features, including true ribs; alternate-leg swimming; no functional tongue; and no voice and no auditory apparatus. Most frogs lack ribs; exhibit synchronous-leg swimming (a frog kick); and have a functional tongue, a voice, and an auditory apparatus. Tailed frogs also possess a unique set of skin peptides (ascaphins) with both anti-bacterial and anti-fungal properties.
Besides these primitive features, tailed frogs exhibit a number of other life history traits that tie them to permanent intermediate-gradient streams with substrates of at least a moderate clast size in north-temperate forested landscapes. These traits include relatively low temperature requirements, internal fertilization, a highly adhesive egg jelly, a rheophilous larval stage requiring interstitial streambed refuges, and post-metamorphic life stages that sustain high levels of water loss and turnover, have reduced lungs, and are active at extremely low light levels, typically at night. Adult tailed frogs exhibit high site fidelity, and populations appear to persist in streams where the aforementioned habitat characteristics are maintained over time, conditions frequent in perennial headwaters. However, tailed frogs also occur outside of headwater areas, but the actual extent of that distribution is unknown in part because sampling approaches for small headwater streams become less effective as stream size increases, and in part because interactions with other species (especially potential predators) become more frequent in larger streams, both of which may limit detecting tailed frog life stages. Process domain changes that alter flows and substrates, and inter-species interactions may limit tailed frogs in larger streams but the limiting dynamics and how these vary geographically remain largely unstudied.
Tailed frogs are also demographically distinctive. They have relatively low fecundity (a moderate clutch size and typically reproduce every other year), a lengthy larval stage (often more than a year), and a lifespan that may exceed 15 years.
This distinctive combination of features limits tailed frogs to relatively wet forested landscapes such as those found in particular areas of montane and submontane habitats of the PNW. The non-contiguous nature of suitable habitat may explain the divergence of the genus into two species: the Coastal Tailed Frog (Ascaphus truei) found in the Coast Ranges and Cascade Mountains of the Pacific Coast, and the Rocky Mountain Tailed Frog (A. montanus) found in the interiorly located Rocky Mountain axis.
Tailed frogs are of conservation concern throughout much of their geographic ranges because large proportions of their ranges are managed for timber, and disturbance associated with forest practices may reduce tailed frog habitat quality. Timber harvest in headwater stream basins can increase stream water temperature and reduce habitat moisture (through loss of stream and terrestrial canopy cover), increase sedimentation that results in loss of interstitial instream habitat, and contribute wood debris that can bury stream reaches. Tailed frogs appear to be less common in recently harvested areas relative to non-harvested areas, a pattern that may reflect less favorable temperature and moisture conditions or reduced levels of instream interstitial habitat. However, most studies addressing tailed frogs have been retrospective, and have lacked sampling techniques that estimate animal detectabilities. Further, the few experimental studies addressing tailed frogs have lacked statistical power.
In summary, current forest practices may negatively affect tailed frogs, but empirical evidence for this conclusion is weak. To better elucidate the effect of forest practices on tailed frogs, seven issues need address: 1) strengthen inference through manipulative experiments and detectability estimation; 2) consider interactions (biological or otherwise) that might affect treatment and reference sites differently; 3) partition the relative influence of effects generally thought to be positive (increases in productivity due to canopy removal) from those thought to be negative (increases in sedimentation); 4) increase recognition that differences exist in life history between the two tailed frog species that are likely to limit cross-species translation of study results (current understanding of the true level of differences between the two species are limited); 5) carefully consider altitudinal or latitudinal gradients, which modulate tailed frog response to disturbance, for potential inclusion as covariates in landscape-level experiments; 6) carefully consider the contrast between effect sizes and treatment effects in pilot studies prior to committing resources to major field studies; and 7) given the variability in field experiments, consider simulated stream studies in test channels where treatment variables (sediment inputs, temperature and light) can be more tightly manipulated while coupling such experiments in a sensible way to field conditions and experiments. Attention to these areas will greatly improve confidence in study results and the strength of inference from those results.
Despite the fact that sedimentation from roads linked to harvest almost invariably exceeds those of harvest itself, attention has been almost entirely focused on the effects of harvest per se on tailed frogs and other stream-associated amphibians. The one study examining the effects of road building on stream-associated amphibians was done outside of a forestry practices context. Hence, the relationship of common forest practices other than harvest per se on stream-associated amphibians needs attention.
Climate change will no doubt influence tailed frogs, and much of that impact is expected to occur via habitat alteration. The change driver is global in scope, so both currently recognized tailed frog species are likely to be affected rangewide. Moreover, habitat changes arising from climate change are anticipated to dwarf the most severe habitat effects known to affect tailed frogs in both scope and scale. Based on climate change predictions for the Pacific Northwest, we anticipate that significant changes in hydrology and stream temperature will influence tailed frog habitats, especially in headwater streams. Understanding climate change effects on tailed frogs will require experimental designs that consider both the shifts in seasonal temperature patterns and changes in stream hydrology that alter the riparian and stream ecology of their habitats.
... ). However, on the North Fork of the Mad River in northern California, mating is claimed to have been observed only in May, though males with secondary sexual characteristics have been observed in June and July (Sever et al. 2001); the seasonal effort that this assessment is based on is unclear. A few additional breeding observations exist for A. truei in March–May, but these involve individuals introduced into the same container following capture. ...
... Noble made key contributions through his discoveries of sperm in female oviducts, concealed cloacal spines that become visible as blood fills the breeding male "tail", and male ability to direct their "tail" forward and insert it into the female cloaca (Noble 1925, Noble and Putnam 1931). Of the over 6,400 currently recognized species of anurans, A. truei is the only species known to engage in copulation that includes intromission (Sever et al. 2001). In fact, coupling in A. truei has been termed copulexus due to the distinctive combination of amplexus with internal fertilization using the "penis-like" cloacal tail (Sever et al. 2001). ...
... Of the over 6,400 currently recognized species of anurans, A. truei is the only species known to engage in copulation that includes intromission (Sever et al. 2001). In fact, coupling in A. truei has been termed copulexus due to the distinctive combination of amplexus with internal fertilization using the "penis-like" cloacal tail (Sever et al. 2001). Copulexus, which involves an inguinal or pelvic embrace 103 (Noble and Putnam 1931, Slater 1931, Metter 1964b, Wernz 1969), is a highly stereotyped behavior in which males may struggle for hours to gain the proper position before achieving intromission 104 ( Putnam 1931, Metter 1964b). ...
... The unique life history of tailed frogs can result in temporal overlap between the first two periods because of individual and life stage variation. Both species of tailed frogs engage in internal fertilization that involves sperm storage for relatively long intervals (months to perhaps years; A. truei: Noble 1925, Noble and Putnam 1931, Sever et al. 2001; and A. montanus: Metter 1964b). Unlike other frogs in the PNW and elsewhere, this results in the temporal separation of breeding (coupling of adults) and oviposition (the laying of eggs; Brown 1975), a phenomenon that Jameson (1955) first pointed out. ...
... ). However, on the North Fork of the Mad River in northern California, mating is claimed to have been observed only in May, though males with secondary sexual characteristics have been observed in June and July (Sever et al. 2001); the seasonal effort that this assessment is based on is unclear. A few additional breeding observations exist for A. truei in March–May, but these involve individuals introduced into the same container following capture. ...
... Noble made key contributions through his discoveries of sperm in female oviducts, concealed cloacal spines that become visible as blood fills the breeding male "tail", and male ability to direct their "tail" forward and insert it into the female cloaca (Noble 1925, Noble and Putnam 1931). Of the over 6,400 currently recognized species of anurans, A. truei is the only species known to engage in copulation that includes intromission (Sever et al. 2001). In fact, coupling in A. truei has been termed copulexus due to the distinctive combination of amplexus with internal fertilization using the "penis-like" cloacal tail (Sever et al. 2001). ...
... In vertebrates, female sperm storage in dedicated structures occurs in all major lineages with durations ranging from a few hours or days in most mammals (not including bats) to long-term storage up to months in sharks, turtles , birds and also reptiles with a reported maximum of seven years [2] . Among modern amphibians many female salamanders can store sperm in unique cloacal spermathecae [3] and internal fertilising anurans such as tailed frogs (Ascaphus ssp.) have sperm storage in the oviducts [4]. This raises the question whether female sperm storage has also evolved in the third group of extant amphibians, the limbless caecilians [5,6]. ...
... kohtaoensis more closely resembles the situation found in Ascaphus truei, so far the only other amphibian known to have oviductal sperm storage. In A. truei sperm is stored in simple tubular glands equipped with ciliated and secretory cells of the elongated ovisac, the posterior-most part of the oviduct [4] . No generalized information about the exact physiological mechanisms of SSTs is available so far [2]. ...
Female sperm storage has evolved independently multiple times among vertebrates to control reproduction in response to the environment. In internally fertilising amphibians, female salamanders store sperm in cloacal spermathecae, whereas among anurans sperm storage in oviducts is known only in tailed frogs. Facilitated through extensive field sampling following historical observations we tested for sperm storing structures in the female urogenital tract of fossorial, tropical caecilian amphibians.
In the oviparous Ichthyophis cf. kohtaoensis, aggregated sperm were present in a distinct region of the posterior oviduct but not in the cloaca in six out of seven vitellogenic females prior to oviposition. Spermatozoa were found most abundantly between the mucosal folds. In relation to the reproductive status decreased amounts of sperm were present in gravid females compared to pre-ovulatory females. Sperm were absent in females past oviposition.
Our findings indicate short-term oviductal sperm storage in the oviparous Ichthyophis cf. kohtaoensis. We assume that in female caecilians exhibiting high levels of parental investment sperm storage has evolved in order to optimally coordinate reproductive events and to increase fitness.
... In the tailed frog, Ascaphus truei, males have an intromittent organ and copulate with females to transfer sperm. Males in ''copulexus'' (Sever et al., 2001 coined ''copulexus'' to distinguish amplexus leading to copulation from conventional, anuran amplexus) clasp both dorsally and ventrally, and two males clasping a single female has been seen in the field (Stephenson and Verrell, 2003). In laboratory mating trials, two male copulexus also occurs and the dorsal and the ventral males both copulated, sequentially, leading to internal fertilization, sperm storage (Sever et al., 2001), and the potential for 14 ...
... Males in ''copulexus'' (Sever et al., 2001 coined ''copulexus'' to distinguish amplexus leading to copulation from conventional, anuran amplexus) clasp both dorsally and ventrally, and two males clasping a single female has been seen in the field (Stephenson and Verrell, 2003). In laboratory mating trials, two male copulexus also occurs and the dorsal and the ventral males both copulated, sequentially, leading to internal fertilization, sperm storage (Sever et al., 2001), and the potential for 14 ...
... Author's personal copy sperm competition. Internal fertilization occurs in other frog groups (e.g., Sever et al., 2001; Wake, 1980), and there is potential for polyandry because in at least one bufonid species (Nectophrynoides malcolmi), multiple males have been reported to associate with females in amplexus (Wake, 1980). ...
Polyandry and sperm competition have strong impacts on the evolution of animal mating systems but have been ignored in studies of anurans. Polyandry occurs in many forms in frogs, occurs in seven families and is particularly common in the Rhacophoridae. Anuran polyandry is commonly associated with high male bias at breeding sites, but females may also deliberately solicit matings with multiple males. Comparative data sets demonstrate clear effects of polyandry on the evolution of testes size and sperm morphology, and similar patterns occur within species. There is experimental evidence of compatibility effects and that sperm-egg interaction patterns are affected by egg and ejaculate properties. We speculate about the role of polyandry in the evolution of anurans; e.g. impacts on strategic ejaculation and sperm storage organs, on body size, call structure, and anuran diversity. Our review is built around an extensive literature on polyandry in the Australian Myobatrachid frog Crinia georgiana.
... Sperm storage tubules occur in the oviducts of females of Ascaphus truei and Ascaphus montanus, just distal to the region where egg jelly is applied to the eggs (Sever, Moriarty, Rania, & Hamlett, 2001). These two species of frog, found in the northwestern USA and southwestern Canada, have traditionally been the sole members of the family Ascaphidae, usually considered the basal family of frogs. ...
... Ascaphus truei and its sibling species A. montanus are phylogenetically basal frogs that practice internal fertilization. These frogs are the only anurans that truly can be said to engage in copulation while in amplexus (termed 'copulexus' by Sever et al. (2001)), and the only anamniotes to possess a 'true penis;' i.e., a copulatory organ in which cavernous tissue becomes engorged with blood during erection (Sever et al., 2003). The penis has been traditionally referred to as a 'tail,' but it has no relationship to the caudal vertebrae and is a fleshy extension of the cloaca. ...
Gonadal steroid hormones, particularly testosterone (T) and related androgens, are important in the development and seasonal variation of sexually dimorphic organs. Other hormones, such as prolactin, have been found to be necessary in conjunction with gonadal steroids for the full structural development and function of some sex accessory structures (e.g., oviductal and cloacal gland secretions) and secondary sexual characteristics (e.g., genial glands and skin glands of newts). Thyroid hormones work syner-gistically with prolactin and T in hypertrophy of the tail fin and nuptial pads of American newts (e.g., Notophthalmus viridescens), whereas oxytocin antagonizes the influence of prolactin. In the Japanese newt (Cynops pyrrhogaster), however, estrogens block the action of prolactin on increasing tail height, explaining the sexual differences in tail morphology. Arginine vasotocin (AVT) has been shown to stimulate labor in the viviparous salamandrid Salamandra salamandra, corticosterone influences the develop-ment of salamander cloacal glands, and prostaglandin PGF 2a causes the release of sperm from the salamander spermatheca by triggering contraction of the myoepithelium.
... In reptiles, the SSTs are situated within the oviducts themselves (Pearse and Avise 2001; Han et al. 2008). Surprisingly, only one frog species (Ascaphus truei) is known to have evolved the ability to store spermatozoa in oviductal sperm storage tubules (Sever et al. 2001; Sever 2002), but other amphibian groups (salamanders) have evolved cloacal spermathecae that can store spermatozoa for long periods (Sever 1991Sever , 1997Sever , 2002). For the most part, mammalian evolution has ensured that the degree of asynchrony between ovulation and insemination is a matter of only a few hours to several days. ...
... Histological studies of sperm storage organs in this group of species have identified SSTs in birds and reptiles, especially in turtles (Birkhead and Møller 1992; Gist and Fischer 1993; Gist and Congdon 1998), but we cannot conclude from this that the SSTs are exclusively an evolutionary feature of this group; they occur in other taxonomic groups too [e.g. sharks: Storrie et al. (2008) and also (to a very limited extent) in frogs (Sever et al. 2001)]. The single frog species reported as having the ability to store spermatozoa (A. ...
... The observation that SSTs have only evolved in one frog species (A. truei) known to store spermatozoa in the oviduct (Sever et al. 2001; Sever 2002) coupled with the knowledge that SSTs also perform this function in some shark species (Hamlett et al. 2002; Storrie et al. 2008) again suggests that the intimate contact between spermatozoa and oviductal cells provides the appropriate environment for sperm storage. The existence of SST in different species also has the merit of providing a parsimonious and elegant solution to the problem of sperm storage across multiple species. ...
Contents
Once semen has been collected for artificial insemination, it is diluted into extenders designed to prevent its deterioration over the period prior to insemination. If the semen is not frozen, the extenders provide protection for a period of a few hours to a few days, depending on species. Despite the efforts of biotechnologists to increase the duration of storage without compromising fertility, there has been relatively little progress for many years. However, comparative studies in diverse species have revealed that long‐term sperm storage (up to months and years) within the female reproductive tract is relatively commonplace in reptiles, fishes, birds and amphibians. Even among mammals, some species of bat have evolved mechanisms for storing spermatozoa for several months in the uterus or oviduct so that they can mate in the autumn but postpone fertilization until the spring. We currently know little about the mechanisms that support such long‐term sperm storage, mainly because evidence from such species is either absent or fragmentary. Nevertheless, parallels between mammalian and other systems, where spermatozoa are sequestered in sperm storage tubules, suggest that the enclosure of spermatozoa within pockets of epithelial cells may be sufficient to achieve long‐term sperm storage. In addition, recent evidence from sperm‐storing bats has suggested an alternative, or additional, hypothesis that the modulation of apoptosis within epithelial cells is important in controlling sperm survival. Despite a lack of direct experimental evidence from a wide variety of species, I propose that there is now enough evidence to warrant investigation of these hypotheses.
... Female sperm storage has evolved multiple times and occurs in a diverse assemblage of taxa from acoel flatworms (Grae and Kozloff 1999), insects (Eberhard 1997), decapod crustaceans (Salmon 1983), salamanders (Sever et al. 2001), birds (Malecki et al. 2004), to mammals (Taggart and Templesmith 1991). Given the large degree of variation in sperm storage and mating behavior in decapods , comparative studies on this group may explain how mating behavior shapes, and is shaped by, sperm storage (Sainte-Marie 2007). ...
Variation in female sperm storage is explained, in part, by the amount of sperm transferred at mating. Laboratory mating experiments
were conducted on Eurypanopeus depressus and Rhithropanopeus harrisii from the Chesapeake Bay and Pachygrapsus transversus from Florida, while mated pairs of Uca beebei and U. terpsichores were collected from mudflats in Panama. All experiments and collections were conducted during the summer of 2006 and 2007.
More sperm was transferred to larger than smaller females, and by species with long copulation durations (R. harrisii and E. depressus). These two species live in cryptic habitats, have high sperm/egg ratios, and likely store sperm across multiple broods.
In contrast, P. transversus and U. beebei mate conspicuously, have short copulations, transfer fewer sperm, and have low sperm/egg ratios. Comparisons of sperm transfer
across different mating strategies and habitats provide a better understanding of female sperm storage in the Brachyura.
... However, this secretory material possibly has also an important role during egg investment, after fertilization. Female sperm storage is not exclusive to elasmobranchs, occurring in a wide range of vertebrate taxonomic groups that include other fishes, reptiles, amphibians and mammals, and in different organs of the female reproductive tract (Birkhead & Moller, 1993; Sever et al., 2001; Sever & Hamlett, 2002; Holt & Lloyd, 2009). Sperm storage on the OG is documented here, for the first time, in females of C. coelolepis. ...
Sperm storage in males and females was studied for the deepwater shark Portuguese dogfish Centroscymnus coelolepis. In males, sperm is stored in the seminal vesicle from early maturity stages until mating. The epithelium of the seminal vesicle secretes an acid mucopolysaccharide that might preserve sperm until it is released. The oviducal gland (OG) presents the four distinct zones described for other elasmobranchs: club, papillary, baffle and terminal. Mature, pregnant, resting and regenerating females are able to store sperm in the terminal zone. Sperm was found within sperm storage tubules (SSTs), involved by a secretory matrix. The localization of SSTs deeper in the OG suggests long-term sperm storage, which is in agreement with the long reproductive cycle described for this species. Sperm storage is an advantage for this deepwater species that presents sexual segregation and lives in a food-constrained environment, increasing the efficiency in reproduction.
