18 research outputs found
Impact of Tail Loss on the Behaviour and Locomotor Performance of Two Sympatric Lampropholis Skink Species
Caudal autotomy is an anti-predator behaviour that is used by many lizard species. Although there is an immediate survival benefit, the subsequent absence of the tail may inhibit locomotor performance, alter activity and habitat use, and increase the individuals' susceptibility to future predation attempts. We used laboratory experiments to examine the impact of tail autotomy on locomotor performance, activity and basking site selection in two lizard species, the delicate skink (Lampropholis delicata) and garden skink (L. guichenoti), that occur sympatrically throughout southeastern Australia and are exposed to an identical suite of potential predators. Post-autotomy tail movement did not differ between the two Lampropholis species, although a positive relationship between the shed tail length and distance moved, but not the duration of movement, was observed. Tail autotomy resulted in a substantial decrease in sprint speed in both species (28–39%), although this impact was limited to the optimal performance temperature (30°C). Although L. delicata was more active than L. guichenoti, tail autotomy resulted in decreased activity in both species. Sheltered basking sites were preferred over open sites by both Lampropholis species, although this preference was stronger in L. delicata. Caudal autotomy did not alter the basking site preferences of either species. Thus, both Lampropholis species had similar behavioural responses to autotomy. Our study also indicates that the impact of tail loss on locomotor performance may be temperature-dependent and highlights that future studies should be conducted over a broad thermal range
Embryonic Gonadal and Sexual Organ Development in a Small Viviparous Skink, Niveoscincus ocellatus
The majority of research into the timing of gonad differentiation (and sex
determination) in reptiles has focused on oviparous species. This is largely because: (1) most reptiles
are oviparous; (2) it is easier to manipulate embryonic developmental conditions (e.g., temperature)
of eggs than oviductal embryos and (3) modes of sex determination in oviparous taxa were thought
to be more diverse since viviparity and environmental sex determination (ESD)/temperaturedependent
sex determination (TSD) were considered incompatible. However, recent evidence
suggests the two may well be compatible biological attributes, opening potential new lines of enquiry
into the evolution and maintenance of sex determination. Unfortunately, the baseline information
on embryonic development in viviparous species is lacking and information on gonad differentiation
and sexual organ development is almost non-existent. Here we present an embryonic morphological
development table (10 stages), the sequence of gonad differentiation and sexual organ development
for the viviparous spotted snow skink (Niveoscincus ocellatus). Gonad differentiation in this species
is similar to other reptilian species. Initially, the gonads are indifferent and both male and female
accessory ducts are present. During stage 2, in the middle third of development, differentiation
begins as the inner medulla regresses and the cortex thickens signaling ovary development, while the
opposite occurs in testis formation. At this point, the Mu¨llerian (female reproductive) duct regresses
in males until it is lost (stage 6), while females retain both ducts until after birth. In the later stages
of testis development, interstitial tissue forms in the medulla corresponding to maximum
development of the hemipenes in males and the corresponding regression in the females