Animal species are delimited by reproductive isolation mechanisms (RIMs). Postzygotic RIMs are mainly products of genetic differences and thus their strength increases with elapsed divergence time. The relationship between postzygotic reproductive isolation and genetic divergence, however, differs considerably among major clades of vertebrates. We reviewed the available literature providing empirical evidence of natural and/or experimental hybridization between distinct species of lizards (squamates except snakes). We found that hybridization events are widely distributed among nearly all major lizard clades. The majority of research focuses on parthenogenetic species and/or polyploid hybrids in families Lacertidae, Teiidae and Gekkonidae. Homoploid bisexual hybrids are mainly reported within Lacertidae and Iguania groups. As a proxy of genetic divergence of the hybridizing taxa we adopted nucleotide sequence distance (HKY85) of mitochondrial cyt b gene. The upper limit of genetic divergence was similar with regard to both parthenogenetic and bisexual hybrids. Maximum values of these distances between hybridizing species of lizards approached 18%?21%, which is comparable to or even exceeds the corresponding values reported for other principal clades of vertebrates. In spite of this, F1 hybrids are typically at least partially fertile in lizards and thus genetic in-trogression between highly divergent species is possible. The relationship between the genetic distance and hybrid fertility was not found.
An extensive research effort is devoted to the evolution of life-histories and processes underlying the variation in adult body weight; however, in this regard, some animal taxa remain neglected. Here we report rates and timing of growth recorded in two wild-derived populations of a model lizard species, Eublepharis macularius (M, W), other two related species, i.e., E. angramainyu (A) and E. sp. (D), and their between-species hybrids. We detected clear differences among the examined species/populations, which can be interpreted in the terms of “fast – slow” continuum of life-history strategies. The mean asymptotic body size was the highest in A and further decreased in the following order: M, W, and D. In contrast, the growth rate showed an opposite pattern. Counter-intuitively, the largest species exhibited the slowest growth rates. The final body size was determined mainly by the inflexion point. This parameter reflecting the duration of exponential growth increased with mean asymptotic body size and easily overcompensated the effect of decreasing growth rates in larger species. Compared to the parental species, the F1 and backcross hybrids exhibited intermediate values of growth parameters. Thus, except for the case of the F2 hybrid of MxA, we failed to detect deleterious effects of hybridization in these animals with temperature sex determination.
Insect exposure to their predators can affect individuals and community processes, through direct consumption or nonlethal effects. However, the links between behavioral and physiological responses and stimuli needed for the development of predator avoidance are not clear. We subjected desert locusts (Schistocerca gregaria) to three nonlethal treatments, using great tits (Parus major) as a predator. The treatments included: (1) bird—presence of a great tit and its calls, (2) call—great tit calls only, (3) control—absence of a great tit and its calls. In the first behavioral laboratory experiment, locusts were offered food and shelter in an open space. The duration of hiding versus feeding indicated predator responses. In the second laboratory experiment, locusts were subjected to the same three treatments, and adipokinetic hormone (AKH) levels were measured in the central nervous system (CNS) and hemolymph. In the third experiment in an outdoor aviary, birds were allowed to fly freely over locusts before we measured physiological response. During the first experiment, locusts hid for a significantly longer amount of time and fed for a significantly shorter amount of time when the bird was present and calls were played, compared to when only calls were played or compared to the control treatment. The proximity of birds to locusts in the laboratory experiment elicited a significant increase in AKH levels in the CNS and hemolymph compared to the call/control treatment. The physical proximity of the great tits affected both the behavioral and physiological responses of the locusts.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.