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13 Reduced area cladogram for orangethroat whiptail lizards, Cnernidophorus hyperythrus group, on the peninsula of Baja California.
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Early in the history of systematic biology, scientists were interested in documenting the wonders of “the creation.” Specimens procured on expeditions were placed in collections, and spectacular hand-colored plates graced giant monographs, showpieces of discovery and exploration. Darwin’s work shifted interests to natural selection and the process...
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Citations
... In general, the islands in the Gulf of California can be classified into three categories: (1) land-bridge islands (cf. continental shelf of Ali 2017), which were connected to land but became isolated with the rise in sea level during the Pleistocene glaciations (Grismer 2002); (2) continental (see different types in Ali 2017), which were once connected to the peninsula or mainland but later became separated by the displacement of tectonic plates and are now surrounded by deep water (see discussion on the origin of Ángel de la Guarda by Murphy and Aguirre-León 2002); and (3) oceanic (see different types in Ali 2017), those that have not had contact with the Baja California peninsula or mainland Mexico, having emerged from the sea, and are thus surrounded by deep water. Because the exact origin of some islands with no recent connection to the peninsula or mainland is not known (see examples in Murphy and Aguirre-León 2002), we use in some analyses a simpler classification with two island types: "oceanic" (oceanic + continental) and land-bridge islands (Table 8.1). ...
... continental shelf of Ali 2017), which were connected to land but became isolated with the rise in sea level during the Pleistocene glaciations (Grismer 2002); (2) continental (see different types in Ali 2017), which were once connected to the peninsula or mainland but later became separated by the displacement of tectonic plates and are now surrounded by deep water (see discussion on the origin of Ángel de la Guarda by Murphy and Aguirre-León 2002); and (3) oceanic (see different types in Ali 2017), those that have not had contact with the Baja California peninsula or mainland Mexico, having emerged from the sea, and are thus surrounded by deep water. Because the exact origin of some islands with no recent connection to the peninsula or mainland is not known (see examples in Murphy and Aguirre-León 2002), we use in some analyses a simpler classification with two island types: "oceanic" (oceanic + continental) and land-bridge islands (Table 8.1). Table 8.1). ...
... As for the origin of snakes from oceanic islands of the Gulf of California, immigration through over-water dispersal may be the process involved in most cases (Murphy and Aguirre-León 2002; see review in Martins and Lillywhite 2019). The heavy rainfall that occurs in the region-due to the presence of tropical stormsbrings from the Baja California Peninsula plants, trunks, and roots in conglomerates in the form of "floating islands", which can transport live animals; snakes are specially able to persist for long periods in these "floating islands" (see Martins and Lillywhite 2019). ...
A total of 31 islands in the Gulf of California harbor 38 species of snakes, with up to 13 occurring on a single island. Island area explained 57% of the species richness, whereas isolation was less important. Species richness was not different between oceanic and land-bridge islands. Islands with endemics (occurring on a single island) tended to be more isolated but were not different in area from islands without endemics. Only one species of insular snake from the Gulf, Crotalus catalinensis, is threatened globally, and six are in the Amenazada category of Mexico. The main threats to island snakes are invasive species, killing and illegal collection, human disturbances, and natural disasters. Important conservation actions that benefit island snakes are protected areas, education, and ex situ populations. The authors recommend studies exploring patterns of phylogenetic and functional diversity in the Gulf of California islands to better assess and conserve their biodiversity.
... Previously, however, Petren and Case [120] found genetic evidence that determined that this population belongs to S. a. slevini. Murphy and Aguirre-León [121] recognized this population as S. slevini. Finally, Montanucci [122] reviewed the morphological evidence and concluded that, indeed, the Chuckwallas from Danzante resemble S. slevini. ...
... Uta antiqua was described as a new species (as U. antiquus) from Isla Salsipuedes, San Lorenzo Norte, and Sur [129], and recognized as valid by Liner [130,131] as well as Murphy and Aguirre-León [121,132]. Grismer [83] synonymized U. antiqua with U. stansburiana. Flores-Villela and Canseco-Márquez [133] and Wilson et al. [25] accepted this disposition. ...
... Furthermore, introgression and interbreeding among different populations has occurred often. Also, many insular populations might be translocated and/or introduced [121]. Thus, determining how many insular lineages constitute undescribed species remains challenging. ...
The herpetofauna of the insular systems of Mexico is composed of 226 species, of which 14 are anurans, two are salamanders, and 210 are reptiles, comprised of two crocodilians, 195 squamates, and 13 turtles. Although the surface of the Mexican islands is only 0.26% of the Mexican territorial extension, these 226 species constitute 16.1% of Mexico’s documented herpetofauna of 1405 species. We classified the Mexican islands into five physiographic regions: the islands of Pacific Baja California; the islands of the Gulf of California; the islands of the Tropical Pacific; the islands
of the Gulf of Mexico; and the islands of the Mexican Caribbean. The highest species richness among these regions is in the Gulf of California, with 108 species, and the lowest richness is 40 for the islands of the Pacific Baja California and 46 for those of the Gulf of Mexico. We identified introduced species, risk of wildfires, climate change, and urban/tourist development as the main environmental threats impinging on these species. In addition, we assessed the conservation status of the native species by comparing the SEMARNAT (NOM-059), IUCN Red List, and the Environmental Vulnerability Score (EVS) systems. The comparison of these systems showed that the NOM-059 and the IUCN systems seriously underestimate the degree of threat for insular endemics, being particularly concerning for those insular species that are known only from their respective type localities. The EVS system proved to be practical and indicated that 94 species have a high vulnerability status, 62
a medium status, and 56 a low status. The Relative Herpetofaunal Priority system, which contrasts the number of endemic and threatened species among different physiographic areas, indicates that the regions with the highest priority are the Islands of the Gulf of California, followed by the islands of the Tropical Pacific. Finally, we discussed the completeness of the Mexican Natural Protected Areas on the insular systems of the country; the result is outstanding since Mexico is already close to achieving the goal of having all their islands under some degree of federal protection.
... The Side-blotched Lizard is a common widespread generalist, occurring in the western United States, northern Mexico, and along the Baja California Peninsula and many of its associated islands (Grismer 2002). Interestingly, U. stansburiana is present on islands in the Sea of Cortes and Pacific Ocean, and on those with both continental and oceanic origins (Murphy and Aguirre-León 2002), some of which also are associated with endemic species of Uta (Grismer 2002). Certainly, many of those populations are natural overwater dispersal colonizers and, taking into account the anthropological evidence of translocations, some insular populations, assuredly, could be introduced (Murphy and Aguirre-León 2002). ...
... Interestingly, U. stansburiana is present on islands in the Sea of Cortes and Pacific Ocean, and on those with both continental and oceanic origins (Murphy and Aguirre-León 2002), some of which also are associated with endemic species of Uta (Grismer 2002). Certainly, many of those populations are natural overwater dispersal colonizers and, taking into account the anthropological evidence of translocations, some insular populations, assuredly, could be introduced (Murphy and Aguirre-León 2002). This assertion seems to be supported at least by the Uta populations on Isla La Raza, a tiny volcanic island in the Sea of Cortes, where molecular evidence suggests colonization from the north, from Ángel de la Guarda and/or Isla Mejía populations, something that Murphy and Aguirre-León (2002) considered unlikely by natural over water current dispersal, since the severe upwellings in that area should impede that movement. ...
... The occurrence of Peninsular Leaf-toed Gecko (Phyllodactylidae) on Isla Tiburón could be due to natural over-water island hopping, accidental introduction (Murphy and Aguirre-León 2002), ancient historical translocation from other islands in the Sea of Cortes (Nabhan 2000), or even by paleotectonic activity (Blair et al. 2009). Without specific evidence to support any of the above-mentioned scenarios, we elect not to list this species as introduced at this time, but it is certainly a candidate worth further investigation. ...
Among the principal causes producing detrimental effects on global biodiversity are introductions of alien species. Very few attempts to control introduced amphibians and reptiles in Middle America (Mexico and Central America) can be identified, so listings are provided for 24 exotic species, 16 translocated species, and 11 species that were removed from the introduced species listing because of lack of substantiating evidence that they are from established populations. Biosecurity methods are also identified that can be applied for preventing, controlling, and managing introduced and especially invasive species.
... In this context, the Gulf of California (GC) and the adjacent Baja California Peninsula (BCP) provide an ideal study region. The geomorphological history of the Gulf has been particularly dynamic (Dolby, Bennett, Lira-Noriega, Wilder, & Munguía-Vega, 2015;Murphy & Aguirre-Leon, 2002;Umhoefer et al., 2018), and its current oceanographic conditions show high temporal and spatial variability (Ortega, Álavarez-Borrego, Arriaga, Renner, & Bridge, 2010). The processes underpinning the formation of the GC and the BCP are thought to have started ~12 million years ago (Mya), with the detachment of a proto-peninsula from the mainland and the formation of the southernmost GC (Dolby et al., 2015;Umhoefer et al., 2018). ...
... At that time, the southernmost part of the GC was connected to the Pacific Ocean by seaways between islands. By ~3 Mya emerging land attached these islands and the proto-peninsula, closing the seaways and forming the BCP (Dolby et al., 2015;Murphy & Aguirre-Leon, 2002). In spite of these key events between ~6 and 3 Mya, the Colorado river delta established 4.5 Mya but continued to experience smaller fluctuation after that time (Dorsey, O'Connell, McDougall, & Homan, 2018); the Ballenas Channel formation was completed only ~2 Mya (Nagy & Stock, 2000); and recent volcanic activity and overriding plate uplifts changed dramatically the south-west coast of BCP ~2-1 Mya (García Sánchez et al., 2019;Mark, Chew, & Gupta, 2017;Sutherland et al., 2012). ...
Aim
During ecological speciation, reproductive isolation is predicted to evolve between populations adapted to different biotic or abiotic environments despite the absence of geographical isolation. Regions of oceanographic heterogeneity (e.g. current interfaces, habitat transition zones, ecological gradients) are strong candidates for the presence of ecologically divergent natural selection, but their role in the radiation of elasmobranch species is yet to be tested. We used an integrative framework to assess the relative influence of oceanographic heterogeneity and geological history on the diversification of an elasmobranch genus.
Location
Gulf of California (GC) and Baja California Peninsula (BCP), Mexico.
Taxon
Shovelnose guitarfish (genus Pseudobatos).
Methods
We sampled 210 Pseudobatos specimens from four distinct but physically connected oceanographic regions within the GC and in the BCP. We used genetic (mtDNA sequences and AFLP genotypes) and environmental (six oceanographic variables) datasets to clarify phylogenetic relationships, demographic history and evolutionary divergence among populations, and to test for associations between ecologically driven selection and reproductive isolation.
Results
Phylogenetic and population genetic evidence exposed five distinct lineages of Pseudobatos in the region, including four cryptic lineages in the GC. Phylogeographic analyses indicate a recent history of ecologically driven diversification associated with the Gulf's young oceanographic environment and its four ecologically discrete regions. This hypothesis was supported by seascape genetics, ecological niche modelling and by tests of selection.
Main conclusions
We propose an adaptive radiation for the genus Pseudobatos linked with habitat heterogeneity of the GC. Our study likely represents the first assessment of an ecological radiation in the highly diverse elasmobranch group. It capitalizes on the environmental and biogeographic settings of the GC to offer a new perspective about the application of integrative approaches to study divergent natural selection and diversification in the sea.
... However, the narrow continental shelf of the eastern Pacific may have reduced the impact of sea level changes in the region, which remained in its present-day configuration for the majority of the Pleistocene, including during the last glacial maximum (figure 3 in Ludt and Rocha, 2015). Similarly, the shape and location of the Gulf of California reached the approximate present-day shape by the early-mid Pleistocene, around~1 MYA (Murphy and Aguirre-León, 2002), and populations of rocky-shore fishes in Baja have been in continuous residence through the Pliocene and Pleistocene (Riginos, 2005). For taxa distributed in the TEP, including the middle and southern Gulf of California, this long-term relative stability may have enabled a steady, suitable, and habitable coastal area, allowing regional persistence of populations, thus dampening population declines during glaciation cycles and facilitating population expansions, as has been reported in other regions and species during this period (Hoareau et al., 2012). ...
... The population of Carmen Island ( figure 1P; C. s. occultus) showed the largest distance throughout the statistical parsimony network, with 19 mutation steps from all other populations (Álvarez-Castañeda and Murphy 2014: figure 3). The matrilineal patterns of orange-throated lizards (Aspidoscelis hyperythra) showed their origin near Carmen Island ( Radtkey et al. 1997;Murphy and Aguirre 2002), supporting the ancient isolation of this island from the peninsula. On the other hand, Soulé and Sloan (1966) proposed that Carmen Island was connected to the peninsula through a land bridge during the LGM. ...
Adaptation and evolution of terrestrial vertebrates inhabiting islands have been the topic of many studies, particularly those seeking to identify trends or patterns in body size in mammals, albeit not necessarily in shape, in relation to mainland populations. The spiny pocket mouse, Chaetodipus spinatus, is distributed in the Baja California peninsula and its surrounding islands. Insular populations became isolated ~12,000 due to changes in sea level; these populations’ matrilinear (mitochondrial) DNA shows minor interpopulation variation. We tested the hypothesis that adaptation and evolution in these island populations involve variation in both skull size and skull shape (using geometric morphometrics) relative to mainland populations, rather than only in size as previously assumed. A total of 363 specimens from 15 insular and peninsular populations were used in analysis of the skull length and geometric morphometric analyses. Our findings revealed significant differences related to skull size among population. The skull shape analyses showed two significantly different morphotypes: one for all island specimens and one for all mainland samples. Our analyses support the hypothesis that insular populations may not only vary in size relative to mainland populations, but may also show variations in shape, regardless of differing conditions across islands.
... In addition, 6 species of raptors, owls, and goatsuckers, as well as 5 species of shoreline birds, occur on the island (Cody and Velarde 2002). There are 10 species of native reptiles on Santa Catalina Island (Murphy and Aguirre-León 2002) 2 4 6 • I s l a n d s a n d s n a k e s Only the lizard Aspidoscelis tigris and the blind snake Rena humilis are not endemic to the island. ...
... The genus Crotalus is represented in Mexico by 41 species (91%) of the 45 described, and several populations or species occur on islands around the peninsula of Baja California (Grismer 2002). Molecular evidence indicates that C. catalinensis originated from an isolated population of Crolatus ruber during the Pleistocene (Murphy and Crabtree 1985;Murphy and Aguirre-León 2002;Murphy et al. 2002a;Castoe and Parkinson 2006). Its maximum total length is 731 mm, and it has two color patterns-one grayish and one brownish (Figure 10.8). ...
... La transgresión del Golfo de California que separó a la península de Baja California de California y Arizona hace 3 Ma (Riddle et al., 2000;Hafner & Riddle, 2005), y la formación del canal medio peninsular en el desierto del Vizcaíno en el Pleistoceno medio (1.6 Ma) (Hafner & Riddle, 2005;Crew & Hedin, 2006), pudieron originar que estas especies quedaran confinadas en esta región. Una hipótesis alternativa para la distribución discontinua peninsular es la reducción del área de distribución de estas especies que históricamente era más amplia en la península durante el Pleistoceno-Holoceno, pero que con los cambios climáticos de los últimos 10,000-20,000 años (Riddle et al., 2000) se extinguieron en la parte central a causa del incremento de la aridez, dando por resultado que especies con afinidad más mésica permanecieran en la Región del Cabo, o que por su intolerancia al frío del desierto del Hemisferio Norte, tuvieron que buscar refugio en zonas más húmedas (Murphy & Aguirre-León, 2002;Garrick et al., 2013). Un ejemplo es el de Pardosa sierra (Banks, 1898) que quedó confinada al norte y sur de la península durante los periodos glaciares e interglaciares del Pleistoceno y que actualmente es localizada solo en ambientes húmedos a lo largo de la península de Baja California (Jiménez et al., 2015;González-Trujillo et al., 2016). ...
Se dan a conocer 11 nuevos registros de arañas para la Región del Cabo, península de Baja California. Dos son nuevos registros para México (Tennesseellum gollum y Araneus illaudatus); dos géneros (Edricus y Pozonia) y siete especies son nuevos registros para Baja California Sur (Eustala emertoni, Arctosa minuta, Frontinella pyramitela, Chrysso albomaculata, Ariamnes mexicanus, Neospintharus baboquivari y Xysticus californicus). Se reconfirma a Phioponella arizonica para esta región. Se discute la distribución discontinua peninsular y la distribución discontinua peninsular-continental de estas especies.
... Being composites of paternal and maternal genealogies, all sexually reproducing individuals are "polyphyletic" in macroevolutionary terminology. Because of this problem and others, at the microevolutionary level the terms polygenealogical and paragenealogical better represent polyphyletic and paraphyletic, respectively (Murphy and Aguirre-Léon, 2002). Given that all individuals are polygenealogical, this terminology makes no taxonomic inference. ...
... The absence of monogenealogy in C. cattienensis is analogous to that for many insular species of lizards on islands in the Gulf of California where a large mtDNA discontinuity occurs for most species in the middle of the Baja California peninsula; some insular species are more closely related maternally to southern peninsular lizards than to northern ones, and the same is true for northern insular lizards being associated with northern sites (Upton and Murphy, 1997;Murphy and Aguirre-Léon, 2002). For Baja California, this pattern involves morphologically distinct insular species and it points to the problem of applying macroevolutionary terminology, especially the requirement of monophyly, to genealogical patterns (Murphy and Aguirre-Léon, 2002;Murphy and Méndez de la Cruz, 2010). ...
... The absence of monogenealogy in C. cattienensis is analogous to that for many insular species of lizards on islands in the Gulf of California where a large mtDNA discontinuity occurs for most species in the middle of the Baja California peninsula; some insular species are more closely related maternally to southern peninsular lizards than to northern ones, and the same is true for northern insular lizards being associated with northern sites (Upton and Murphy, 1997;Murphy and Aguirre-Léon, 2002). For Baja California, this pattern involves morphologically distinct insular species and it points to the problem of applying macroevolutionary terminology, especially the requirement of monophyly, to genealogical patterns (Murphy and Aguirre-Léon, 2002;Murphy and Méndez de la Cruz, 2010). ...
Examples of cytonuclear discordance (CD), i.e. differing branching patterns from mitochondrial and nuclear DNA data, are increasing. This raises concerns about combining data from the two genomes for the purpose of reconstructing phyletic history. Because of this, we explore the efficacy of DNA barcoding based on the gene cytochrome c oxidase subunit I (COI; Entrez COX1) from the perspective of two nuclear DNA (nDNA) loci: RPL35 and RAG1. Our analyses use 164 samples of Vietnamese bent-toed geckos of the Cyrtodactylus irregularis species complex (Reptilia: Gekkonidae) collected from 24 localities and 306 new sequences. DNA barcoding infers the presence of ten described species and identifies at least 11 unknown lineages from different areas. K2P genetic distances between sites average 16.6 ± 4.6%. Phylogenetic analyses of nuclear DNA data resolve two strongly supported main clades that correspond with northern and southern groups of geckos and presence or absence of enlarged fermoral scale rows. The matrilineal genealogy and nDNA phylogeny are concordant in resolving major lineages, yet trees derived from the two sets of data, and a combined mtDNA-nDNA dataset, are significantly incompatible (AU test: p < 0.01). The extent of CD precludes combining the two genomes for a single analysis. Analyses of both genomes suggest the presence of at least five undescribed cryptic species. Geckos at one site, Ta Kou Mountain, have a complex history involving the unification of two divergent matrilines (K2P = 10.2%). Analyses of nDNA markers alone does not recover this event because gene flow has erased the historical signal. Finally, the independent and geographically isolated lineages face a battle for survival owing to continued habitat destruction. Urgent conservation planning and implementation is necessary for many sites.
... The Baja California Peninsula (BCP; Fig. 1) has been a model landscape for phylogeographic studies due to its geographic isolation, landscape heterogeneity and high levels of endemism (Jezkova et al. 2009;Wilson & Pitts 2012;Graham et al. 2014;Dolby et al. 2015). In several studies, population divergences or phylogeographic breaks have been detected in a diversity of taxa (Upton & Murphy 1997;Riddle et al. 2000;Murphy & Aguirre-León 2002;Nason et al. 2002;Zink 2002a;Crews & Hedin 2006;Lindell et al. 2006;Graham et al. 2014;Lira-Noriega et al. 2015). To explain the causes of such phylogeographic breaks, hypotheses that include vicariance events have been proposed, with the most important being these: (1) the marine transgression of the Gulf of California in the northern-gulf region (south of California and Arizona), with separation from the rest of the BCP occurring 3 million years ago (Mya) (Riddle et al. 2000;Hafner & Riddle 2005); (2) the mid-peninsular channel, which formed approximately 1 to 1.6 Mya in the nearby Vizcaíno Desert (Upton & Murphy 1997;Hafner & Riddle 2005;Crews & Hedin 2006;Lindell et al. 2006); and (3) the Isthmus of La Paz Channel, which separated the Cape Region of the BCP 3 Mya (Riddle et al. 2000;Hafner & Riddle 2005;Garrick et al. 2013). ...
... 21,000 years ago (Dansgaard et al. 1993) may have forced many species from the deserts of the Northern Hemisphere to find refuge south of their previous distributions (Hewitt 1996(Hewitt , 2000(Hewitt , 2004Van Devender 2002;Graham et al. 2013;Harl et al. 2014). The Cape Region, at the southern tip of the BCP, was likely used as a refugium for species that could not tolerate cold (Murphy & Aguirre-León 2002;Garrick et al. 2013). However, the number and location of refugia is species dependent, as each likely responded differently to climatic events (Harl et al. 2014). ...
... Although a phylogeographic break was observed around the mid-peninsular channel and Isthmus of La Paz (Crews & Hedin 2006) in spiders of the genus Homalonychus Marx, 1891 (Homalonychidae), in our study phylogeographic breaks were not detected among P. sierra populations along the BCP (Fig. 3). These results and a paucity of geological evidence refute the hypothesis of the occurrence of a mid-peninsular channel (Grismer 2002;Murphy & Aguirre-León 2002;Crews & Hedin 2006;Garrick et al. 2009), or if it did exist, it did not have a lasting impact on the genetic structure of P. sierra in this region. Indeed, although the signal from the CO1 data did not reveal population expansion, the wide distribution of a single haplotype (Hap1), the few haplotypes with restricted distribution (Fig. 2b) and the divergence time inferred (Fig. 4) all suggest that P. sierra populations were already present along the BCP at least 2.4 Mya. ...
The phylogeographic structure of some species distributed across the Baja California Peninsula has been traditionally hypothesized as resulting from vicariant events thought to have occurred between 1-3 Mya. Climatic fluctuations during the Pleistocene have also been shown to influence the distribution patterns of species, and vicariant patterns may have been erased as a consequence of population contractions or expansions into or out of refugia generated during the last glacial maximum ca. 21,000 years ago. Thus, there is still some uncertainty regarding the relative role of vicariance in shaping the modern biota of Baja California. To understand the evolutionary history of the wolf spider Pardosa sierra Banks, 1898 on the peninsula, a phylogeny of this species and closely related taxa was generated using a fragment of the mitochondrial gene cytochrome c oxidase subunit I (CO1). Sequences of a fragment of the CO1 gene for 38 individuals from 14 sampling sites along the entire distribution range of P. sierra were used to infer phylogeographic patterns, and five nuclear microsatellite loci were also used to genotype 296 individuals from seven of these 14 locations. The current and past potential distributions from two Pleistocene periods were estimated using niche-based distribution modeling, and scenarios of colonization from detected refugia were simulated. We found that Californian populations of P. sierra diverged from peninsular populations 4 Mya, this divergence coinciding with the northern-gulf split. However, we did not detect genetic breaks in regions where the mid-peninsular and Isthmus of La Paz canals were presumably formed, either with mitochondrial DNA sequences or microsatellite loci. Two refugia were further detected at the geographic ends of the peninsula, these likely preceding subsequent habitat expansion.
