Jorgelina M. Boretto

Categorización del estado de conservación de las lagartijas y anfisbenas de la República Argentina

Luego de la elaboracion de la primera lista roja de la herpetofauna de la Republica Argentina,realizada en el ano 2000, son numerosos los cambios y estudios efectuados en los diferentesgrupos de saurios de la Argentina. Si bien hay avances realizados en todas las ramas de labiologia relacionadas a las lagartijas, los progresos taxonomicos y ecologicos son los mas evidentes.Debido a estos progresos, y a la implementacion de sustanciales modificaciones conrespecto a la metodologia que se utilizara en el ano 2000, un grupo de veintisiete especialistasde diferentes instituciones academicas de la Argentina aportaron informacion biologica, ecologica,geografica y taxonomica en un taller que permitio reevaluar el estado de conservacionde las 256 especies de lagartijas y anfisbenas de la Argentina. Los resultados obtenidos indicanque setenta y ocho especies se encuentran incluidas en la lista roja (una En Peligro, nueveAmenazadas y 68 Vulnerables), 31 Insuficientemente Conocidas y 147 No Amenazadas. Conrespecto a la categorizacion anterior de la AHA, se agregaron 94 especies, de las cuales 87 sonnuevos taxa, cuatro revalidadas, y otras tres especies fueron incorporadas a la fauna argentina.Asimismo cinco especies fueron extraidas del listado de la fauna de la Republica Argentina.En comparacion con los resultados obtenidas en la categorizacion del ano 2000, observamosque el numero de especies Amenazadas se incremento de cinco a nueve especies y de siete a68 especies como Vulnerable, incluyendo a los generos Phymaturus y Anisolepis. Asimismo, sexa0categorizo como Insuficientemente Conocida a 31 especies contra 108 del ano 2000. Estos resultados son en parte debido al incremento en el conocimiento sistematico, biologico, ecologico y biogeograficos de las lagartijas y anfisbenas de la Argentina, por el cambio radical de la metodologia utilizada y tambien por los efectos de la presion antropica sobre las especies y/o sus habitats.

Reproductive biology and sexual dimorphism of a high-altitude population of the viviparous lizard Phymaturus punae from the Andes in Argentina

Phymaturus punae is a viviparous lizard endemic to the Provincial Reserve San Guillermo, San Juan (Argentina). We present the first life history data of P. punae , belonging to an interesting genus adapted to cold climates. Females reach sexual maturity at 80.6 mm, and males at 84.4 mm snout-vent length. There is sexual dimorphism represented by larger and more robust males, but females show a wider body and a proportionally greater interlimb length than males. In males, spermatozoa become abundant in both testes and epididymi in mid-summer. Vitellogenic and pregnant females occurred simultaneously in late spring and mid-summer indicating a biennial reproductive cycle.

Phymaturus of Patagonia, Argentina: Reproductive Biology of Phymaturus zapalensis (Liolaemidae) and a Comparison of Sexual Dimorphism within the Genus

Abstract Lizards of the viviparous genus Phymaturus inhabit regions in which a significant proportion of the year is unsuitable for growth and reproduction. All Phymaturus studied have shown biennial female reproductive cycles. We studied the reproductive biology of Phymaturus zapalensis, which lives on rocky outcrops in cold and arid environments of Patagonia, Argentina. Male and female reproductive cycles, mean annual reproductive output, and sexual dimorphism were analyzed. Additionally, new dimorphic traits of Phymaturus antofagastensis and Phymaturus tenebrosus were compared with published data. The female reproductive cycle of P. zapalensis is annual-biennial (because of skipping a year of reproduction), and synchronous with the annual male reproductive cycle. In midspring, males show spermatozoa in epididymis, and females have enlarged follicles, characteristic of imminent ovulation. The presence of 45% of the adult females with oocytes smaller than 4 mm, in all months of capture except October, suggests a year of skipped reproduction. Female P. zapalensis had greater SVL and a relative larger interlimb length than males. Males exhibited relatively greater head width, neck width, and diameter of front and hind legs. Our data indicate that the potential for annual reproduction exists in this biennial breeding genus. The capability of P. zapalensis to perform either an annual or biennial reproductive cycle, instead of the characteristic biennial cycle of the genus, could be the result of a longer activity season, higher temperatures during spring, summer, and autumn months, together with a high-energy omnivorous diet.

Thermal effects on locomotion in the nocturnal gecko Homonota darwini (Gekkonidae)

Nocturnal lizards show a complex adaptation to environmental temperature. They obtain heat from the substratum, using daytime for performing physiological functions inside thermally suitable shelters, and night-time which involves locomotion and loss of heat for capturing prey. Homonota darwini, the southernmost geckonid in the world, is a small nocturnal insectivorous gecko that occurs in saxicolous habitats of Patagonia, Argentina. Geckos were captured by hand during the day on a rocky hill near Bariloche (Rio Negro, Argentina) in spring and summer. All the geckos were active during daytime and had good limb mobility with a median body temperature of 23 ◦ C. Body temperatures showed a direct dependence on the temperature of the roof of the shelter and on the air temperature. Geckos were made to run on a horizontal track and running speed was measured in two experiments: long runs (1 m) and sprint runs (0.20 m) during the day (diurnal) and at night (nocturnal). Speed was significantly greater in sprints than in long runs and speed increased with body temperature, reaching a maximum at a body temperature of 22 ◦ C. Thus, we conclude that, although the low temperatures of Patagonia impose heavy constraints on the physiological performance of Homonota darwini, they have a peculiar arrangement of mechanical and biochemical abilities which allows for resource acquisition at night, using cryptic habits and short sprint runs.

SIGNS OF PARENTAL BEHAVIOR IN LIOLAEMUS ELONGATUS (SAURIA: LIOLAEMIDAE) OF NEUQUÉN, ARGENTINA

Abstract Parental care in reptiles has been correlated with cold climates and harsh environments. We investigated whether behavioral patterns indicating parental care occurred in the lizard, Liolaemus elongatus, a viviparous species found on rocky outcrops of the Argentinean Patagonia. Five pregnant females were captured during the austral summer and brought to the laboratory for observations. The females were filmed for short periods of time during six days after the birth of their young. During that time, the mothers and offspring were presented with three predatory stimuli, a Diplolaemus sexcinctus, a male Liolaemus elongatus, and a stuffed hawk, Elanus leucurus. Their responses were recorded as well as the distance between mothers and offspring during the experiments and when no stimuli were presented. Except for one female, mothers constructed burrows in which the neonates were born. Mothers and their offspring occupied the same shelter for the whole period of observation. When presented with predatory stimuli, females seemed to choose between remaining near or on top of the burrow with the young inside, or moving away from it. When the offspring were out of the burrow, a female occasionally covered a neonate, forming a bridge over it, particularly when threatened. Mothers showed individual variations in the way they responded to the different stimuli that were presented.

Asynchronic steroid activity of Leydig and Sertoli cells related to spermatogenic and testosterone cycle in Phymaturus antofagastensis

The severe environments where Phymaturus lizards inhabit in the Andes highlands and in Patagonia, Argentina, impose restrictions on their reproduction, offering a framework for the development of life history strategies to overcome hard weather conditions. Among them, prolonged female cycles, asynchrony between sexes in receptivity, and sperm storage in males, were described. Asynchrony in the reproductive timing between males and females is a consequence of different energy requirements for gametogenesis, and often imply the existence of cellular mechanisms to enhance fertilization, such as the asynchronic steroid synthesis between testicular compartments, allowing gametogenesis independently of mating. In the present study ultrastructural and hormone assays were combined for the first time in liolaemids. Specifically, morphological features of steroid activity in Leydig and Sertoli cells, and serum testosterone concentrations have been studied in the lizard Phymaturus antofagastensis. Leydig and Sertoli cells presented morphological features characteristic of steroid synthesis during the spermatogenesis, and evident asynchronic steroid production between testicular compartments. Active Sertoli cells and inactive Leydig cells were observed in spring and autumn, while in mid-summer their steroid activity was synchronic in coincidence with maximal abundance of spermatozoa in epididymis. Serum testosterone concentration was at its maximum in mid-summer (126-230 ng ml(-1)), and minimum in late spring (4-24 ng ml(-1)) and early autumn (2-17 ng ml(-1)). In view of these results, P. antofagastensis males show an original approach to adjust their reproductive activity to physiological and environmental constraints at high latitudes and altitudes in the Andean highlands of Argentina.

Thermal physiology of three sympatric and syntopic Liolaemidae lizards in cold and arid environments of Patagonia (Argentina)

The thermal physiology determines the whole biology of ectotherm organisms, by limiting their acquisition and allocation of resources. Herein, we aim to add knowledge on how different species use the thermal resources when they coexist in a habitat, studying the thermal physiology of three sympatric and syntopic liolaemid lizards, Phymaturus querque, Phymaturus zapalensis, and Liolaemus elongatus during the summer season. We measured the body temperatures at capture places, the operative microenvironmental temperatures in the field, and the preferred body temperature in an experimental thermal gradient in the laboratory. We found that the three species are thermoregulators, selecting cooler thermal microenvironments than the ones expected by chance, and even cooler than the temperatures they selected in a laboratory environment. Liolaemus elongatus is a more efficient thermoregulator (Eu2009=u20090.671) than the two Phymaturus species, P. querque (Eu2009=u20090.441) and P. zapalensis (Eu2009=u20090.471), which are moderate thermoregulators and, apparently, specialists in finding specific types of shelters, since they seem to select certain types of rock crevices. Herein, we found that during the summer season, although individuals have access to warm microenvironments, they spend time on cool refuges, probably to prevent overheating. This highlights the importance of an adequate spatial distribution of operative temperatures (Te), more than just a mere availability of appropriate temperatures.

Testosterone Cycle and Regulation of Reproductive Events in the Lizard Phymaturus punae (Liolaemidae) from the Highlands of the Andes, Argentina

Abstract The genus Phymaturus, entirely viviparous and mostly herbivorous, inhabits the cold and harsh environments of the Andean highlands of Argentina and Chile, and the Patagonian steppe of Argentina. Phymaturus punae is a vulnerable lizard endemic to the Biosphere Reserve San Guillermo (National Park and Provincial Reserve) in San Juan (Argentina) that inhabits high altitudes of 3,100–4,200 m. The reproductive cycles of males and females of P. punae have been described previously. Males perform a prenuptial and annual cycle of spermatogenesis, and females reproduce once every 2 yr. As a consequence, the adjustment in the timing of males to the reproductive cycles of females must be very precise to ensure reproductive success. We elucidate the time of mating and the asynchrony of male and female reproductive events in P. punae based on endocrine and ultrastructural studies. Present hormonal results support the idea that copulation in P. punae occurs at the end of the activity season. Ultrastructural features observed in Sertoli and Leydig cells indicate that both types of cells have the potential to synthesize steroid hormones, to support the spermatogenic cycle and the mating period, respectively. In P. punae the cases of temporal asynchrony in steroid activity suggest that this mechanism must be important to start the spermatogenesis in spring, supported by the steroid activity of Sertoli cells, as Leydig cells are inactive. Nevertheless the asynchronic steroid mechanism seems to be more necessary in Phymaturus species with continuous or postnuptial cycles than in species with prenuptial cycles, like P. punae. Resumen El género Phymaturus, enteramente vivíparo y mayormente herbívoro, habita ambientes fríos y rigurosos de la Cordillera de los Andes en Argentina y Chile, y de la estepa Patagónica Argentina. Phymaturus punae es un lagarto vulnerable, endémico de la Reserva de la Biósfera San Guillermo (Parque Nacional y Reserva Provincial) en San Juan (Argentina), que habita a altas altitudes entre los 3.100 y 4.200 metros. Los ciclos reproductivos masculinos y femeninos de P. punae fueron descriptos. Los machos realizan un ciclo espermatogénico anual prenupcial, y las hembras se reproducen una vez cada dos años. En consecuencia, el ajuste de los tiempos de los machos al ciclo reproductivo femenino debe ser muy preciso para asegurar los sucesos reproductivos. Dilucidamos el período de cópula y la asincronía de los eventos reproductivos de machos y hembras de P. punae, en base a estudios endócrinos y ultraestructurales. Los resultados hormonales obtenidos apoyan la idea que la cópula en P. punae ocurre al final de la temporada de actividad. Las observaciones ultraestructurales en células de Sertoli y de Leydig indican que ambos tipos celulares tienen el potencial para sintetizar hormonas esteroideas, para mantener la espermatogénesis y la cópula, respectivamente. En P. punae los casos de asincronía temporal en la actividad esteroidea, sugieren que este mecanismo es importante para iniciar la espermatogénesis en primavera, sostenida por la actividad esteroidea de las células de Sertoli, mientras las células de Leydig están inactivas. No obstante, el mecanismo de asincronía esteroidea parece ser más necesario en especies de Phymaturus con ciclos continuos o postnupciales, que en especies con ciclos prenupciales, como P. punae.

Slow life histories in lizards living in the highlands of the Andes Mountains

In the highlands of the Andes, lizards must balance precisely the allocation of energy for growth and reproduction to ensure their survival. We studied the individuals’ age, growth rates, age at sexual maturity, and maximum life span of the viviparous lizard Phymaturus antofagastensis, endemic of cold and harsh environments at high altitudes in the Andes Mountains of Catamarca province, Argentina. We also estimated key life history parameters like reproductive effort, lifetime reproductive effort, net reproductive rate, and relative reproductive time in P. antofagastensis as well as in other Phymaturus to compare the interplay among growth, maintenance, and reproduction in species that live across a latitudinal and altitudinal gradient. We found that females and males of P. antofagastensis mature late in life, at 6–7xa0years old, respectively, and some individuals reached 20xa0years of age. Adult females showed higher specific growth rates than males and an adult life span of 9xa0years which, due to their biennial reproduction, results in an estimated production of only four litters in life. This species exhibits one of the highest lifetime reproductive efforts described for lizards. Our results indicate the existence of a tradeoff between the number of reproductive events throughout life and reproductive effort devoted to each event in Phymaturus, related to the phylogenetic group. The palluma group shows low reproductive effort but high number of reproductive events throughout their lives, whereas the patagonicus group shows high reproductive efforts in low number of reproductive events.

Effects of Climate and Latitude on Age at Maturity and Longevity of Lizards Studied by Skeletochronology

Longevity and age at maturity are key life-history traits, directly linked to fitness attributes such as survival and reproductive output. It has been proposed that these traits are strongly influenced by environmental factors, such as temperature, seasonality, and precipitations, which determine the existence of a continuum of life-histories that goes from the slow life histories characterized by late maturity and high longevity of cold and highly seasonal climates to the fast life histories characterized by early maturity and low longevity, typical of the tropical climates. However, large-scale studies that address these topics in lizards are scarce and most of them are based on heterogeneous data, which may overlook the real patterns. Using skeletochronology, we studied age at maturity and longevity of two species of Phymaturus lizards, Phymaturus aguanegra from the Andes and Phymaturus zapalensis from the Patagonian steppe (Argentina). Then, we confronted longevity and age at maturity in these species with published skeletochronology-based data on 46 other lizard species to examine possible association of these life-history traits with latitude and mean annual temperature, thermal amplitude, and precipitations. Both Phymaturus species showed late sexual maturity (7 and 8-9u2009years, respectively) and high longevity (16 and 14-15u2009years, respectively) in coincidence with the other species of the genus studied up to date. The phylogenetic comparative analysis revealed that the most important variable in the determination of longevity patterns in the species studied was latitude: at higher latitudes lizards tend to live longer. In contrast, age at sexual maturity was dependent on mean annual temperature most, especially in males, as lizards from hotter climates mature earlier than lizards from cold sites.