George R. Zug

AGE AND GROWTH IN WILD KEMP'S RIDLEY SEATURTLES Lepidochelys kempii FROM SKELETOCHRONOLOGICAL DATA

Skeletochronological analysis provides age estimates, not actual ages, for seaturtles. Unlike age and growth data from captive and headstart turtles, these estimates predict the actual patterns of age and growth in free-living turtles. A moderate-sized sample of 69 Lepidochelys kempii, salvaged from the Atlantic and Gulf coasts of the USA, had straight-line carapace lengths (SCL) of 188–720 mm and age-estimates of 2–15 years. The von Bertalanffy growth model provides the best fit for the age-estimate and size data and predicts maturity between 11 and 16 years, depending upon the body size selected to represent sexual maturity. The logistic growth model suggests later maturity of 13–19 years. Comparison of the Atlantic and Gulf components of the sample suggests a faster growth rate for ridleys in the Gulf of Mexico, although the sizes of the subsamples are too small for this interpretation to be reliable without additional data. Our age and growth estimates indicate that some members of the early cohorts of headstart ridleys are mature and may have nested already.

Estimation of Age in Nesting Female Iguana iguana: Testing Skeletochronology in a Tropical Lizard

Skeletal elements of female Iguana iguana nesting in Panama show a distinct pattern of periosteal rings or marks of skeletal growth (MSGs), thereby indicating a pattern of cyclic growth. The numbers of MSGs, assuming one MSG is formed each year, slightly underestimate the known ages of a small sample of female iguanas. Based on the estimated age data, female iguanas probably reach sexual maturity in their fourth or fifth years. Age estimates and size are poorly correlated, and females nesting for the first time on Slothia are 292-415 mm in body length (SVL) and range in estimated minimum age from 3-8 yr.

The bioinvasion of Guam: inferring geographic origin, pace, pattern and process of an invasive lizard (Carlia) in the Pacific using multi-locus genomic data

Invasive species often have dramatic negative effects that lead to the deterioration and loss of biodiversity frequently coupled with the burden of expensive biocontrol programs and subversion of socioeconomic stability. The fauna and flora of oceanic islands are particularly susceptible to invasive species and the increase of global movements of humans and their products since WW II has caused numerous anthropogenic translocations and increased the ills of human-mediated invasions. We use a multi-locus genomic dataset to identify geographic origin, pace, pattern and historical process of an invasive scincid lizard (Carlia) that has been inadvertently introduced to Guam, the Northern Marianas, and Palau. This lizard is of major importance as its introduction is thought to have assisted in the establishment of the invasive brown treesnake (Boiga irregularis) on Guam by providing a food resource. Our findings demonstrate multiple waves of introductions that appear to be concordant with movements of Allied and Imperial Japanese forces in the Pacific during World War II.

Phylogeny, historical biogeography and body size evolution in Pacific Island Crocodile skinks Tribolonotus (Squamata; Scincidae)

Competition heavily influences the structure of island communities, particularly in species-rich areas. If ecologically similar lineages come into contact following dispersal, selection may favor rapid evolutionary change; if constraints prevent such change, lineage extinction may result. One mechanism for relieving competition among newly sympatric species is the evolution of body size differences, such as through character displacement or size assortment. The Crocodile skinks of the genus Tribolonotus exhibit a threefold variation in body size, and several species occur in sympatry. We use 2252 bp of DNA sequence data spanning two mitochondrial (cyt b and ND2) and three nuclear (C-mos, Rhodopsin and Phosducin) gene regions to reconstruct the phylogeny of Tribolonotus, use it to examine the biogeography of the genus, and test for size assortment or character displacement. We find evidence that Tribolonotus originated on either Greater Bougainville or in New Guinea, and subsequently colonized surrounding islands via multiple colonization events. Our ancestral state reconstructions support multiple instances of parallel and independent change in body size within Tribolonotus. Additionally, we find no evidence for size assortment and conflicting evidence for character displacement, which we argue suggests that character displacement, combined with ecological differences between New Guinean species (T. gracilis and T. novaeguineae), best explains the evolution of body size in the genus Tribolonotus.

A critique of the walk pattern analysis of symmetrical quadrupedal gaits

Abstract The walk pattern method of symmetrical gait analysis does not differentiate between lateral sequence and diagonal sequence gaits in which the forefoot support patterns are identical. Therefore, it is necessary to indicate the sequence of support posture. Gaits of similar support sequence but with different proportions of fore- to hindfoot support per stride are likely to be statistically different. Additional support postures can be incorporated in the walk pattern, thereby permitting a comparison of running and asymmetrical gaits.

Walk pattern analysis of cryptodiran turtle gaits.

Abstract The terrestrial gaits of turtles are compared by combining the walk patterns and gait formulae. Analysis of the gaits by average distance coefficient yielded five similarity groups. The groups do not correspond to known taxonomic or behavioural groups.

Oviduct Modifications in Foam-Nesting Frogs, with Emphasis on the Genus Leptodactylus (Amphibia, Leptodactylidae)

ABSTRACT. Various species of frogs produce foam nests that hold their eggs during development. We examined the external morphology and histology of structures associated with foam nest production in frogs of the genus Leptodactylus and a few other taxa. We found that the posterior convolutions of the oviducts in all mature female foam-nesting frogs that we examined were enlarged and compressed into globular structures. This organ-like portion of the oviduct has been called a “foam gland” and these structures almost certainly produce the secretion that is beaten by rhythmic limb movements into foam that forms the nest. However, the label “foam gland” is a misnomer because the structures are simply enlarged and tightly folded regions of the pars convoluta of the oviduct, rather than a separate structure; we suggest the name pars convoluta dilata (PCD) for this feature. Although all the foam-nesters we examined had a pars convoluta dilata, its size and shape showed considerable interspecific variation. Some of this variation likely reflects differences in the breeding behaviors among species and in the size, type, and placement of their foam nests. Other variation, particularly in size, may be associated with the physiological periodicity and reproductive state of the female, her age, and/or the number of times she has laid eggs.

Rapid forest clearing in a Myanmar proposed national park threatens two newly discovered species of geckos (Gekkonidae: Cyrtodactylus)

Myanmar’s recent transition from military rule towards a more democratic government has largely ended decades of political and economic isolation. Although Myanmar remains heavily forested, increased development in recent years has been accompanied by exceptionally high rates of forest loss. In this study, we document the rapid progression of deforestation in and around the proposed Lenya National Park, which includes some of the largest remaining areas of lowland evergreen rainforest in mainland Southeast Asia. The globally unique forests in this area are rich in biodiversity and remain a critical stronghold for many threatened and endangered species, including large charismatic fauna such as tiger and Asian elephant. We also conducted a rapid assessment survey of the herpetofauna of the proposed national park, which resulted in the discovery of two new species of bent-toed geckos, genus Cyrtodactylus. We describe these new species, C. lenya sp. nov. and C. payarhtanensis sp. nov., which were found in association with karst (i.e., limestone) rock formations within mature lowland wet evergreen forest. The two species were discovered less than 35 km apart and are each known from only a single locality. Because of the isolated nature of the karst formations in the proposed Lenya National Park, these geckos likely have geographical ranges restricted to the proposed protected area and are threatened by approaching deforestation. Although lowland evergreen rainforest has vanished from most of continental Southeast Asia, Myanmar can still take decisive action to preserve one of the most biodiverse places on Earth.

Mortality of sea turtles Caretta caretta in coastal waters of Georgia

Abstract Mortality of loggerhead sea turtles Caretta caretta on the beach at Cumberland Island, Georgia, increased from approximately 20 turtles in 1974 to 187 turtles in 1979. Mortality is greatest in the subadult and old juvenile segment of the population, suggesting that future recruitment into the breeding population may be reduced.

Rediscovery of an endemic vertebrate from the remote Islas Revillagigedo in the eastern Pacific Ocean: the Clarión nightsnake lost and found.

Vertebrates are currently going extinct at an alarming rate, largely because of habitat loss, global warming, infectious diseases, and human introductions. Island ecosystems are particularly vulnerable to invasive species and other ecological disturbances. Properly documenting historic and current species distributions is critical for quantifying extinction events. Museum specimens, field notes, and other archived materials from historical expeditions are essential for documenting recent changes in biodiversity. The Islas Revillagigedo are a remote group of four islands, 700–1100 km off the western coast of mainland México. The islands are home to many endemic plants and animals recognized at the specific- and subspecific-levels, several of which are currently threatened or have already gone extinct. Here, we recount the initial discovery of an endemic snake Hypsiglena ochrorhyncha unaocularus Tanner on Isla Clarión, the later dismissal of its existence, its absence from decades of field surveys, our recent rediscovery, and recognition of it as a distinct species. We collected two novel complete mitochondrial (mt) DNA genomes and up to 2800 base-pairs of mtDNA from several other individuals, aligned these with previously published mt-genome data from samples throughout the range of Hypsiglena, and conducted phylogenetic analyses to infer the biogeographic origin and taxonomic status of this population. We found the Isla Clarión population to be most closely related to populations in the Sonora–Sinaloa state border area of mainland México and Isla Santa Catalina, in the Gulf of California. Based on genetics, morphology, and geographic distributions, we also recognize these two other lineages as distinct species. Our study shows the importance of museum specimens, field notes, and careful surveys to accurately document biodiversity and brings these island endemics (Clarión and Santa Catalina nightsnakes) and mainland population near the Sonora–Sinaloa state border to the attention of conservation biologists currently monitoring biodiversity in these fragile subtropical ecosystems.