Natural parasites in conjunction with behavioral and color traits explain male agonistic behaviors in a lizard.

Male competition conforms to a cost-benefit model, because while aggression may increase reproductive prospects, it can also increase the risk of injury. We hypothesize that an additional cost in aggressive males would be an increase in parasite load associated with a high energy investment into sexual competition. Some of these infections, in turn, may downmodulate the level of host aggression via energetic trade-offs.

Multiple color patches and parasites in : differential relationships by sex and infection.

Parasites generally have a negative influence on the color expression of their hosts. Sexual selection theory predicts resistant high-quality individuals should show intense coloration, whereas susceptible low-quality individuals would show poor coloration. However, intensely colored males of different species of Old and New World lizards were more often infected by hemoparasites.

Phylogenetic analyses reveal that Schellackia parasites (Apicomplexa) detected in American lizards are closely related to the genus Lankesterella: is the range of Schellackia restricted to the Old World?

Background: Species of Schellackia Reichenow, 1919 have been described from the blood of reptiles distributed worldwide. Recently, Schellackia spp. detected in European and Asian lizards have been molecularly characterised.

Evolutionary games, climate and the generation of diversity.

Environmental stochasticity and climate affect outcomes in evolutionary games, which can thereby affect biological diversity. Our maximum likelihood (ML) estimates of replicator dynamics for morph frequency data from control (25 years) and three experimentally perturbed populations (14 years) of side-blotched lizards yield a 3 × 3 payoff matrix in the generalized Rock-Paper-Scissors family; it has intransitive best replies, and each strategy is its own worst reply. ML estimates indicate significant interactive effects of density and temperature on morph frequency.

Does thermal ecology influence dynamics of side-blotched lizards and their micro-parasites?

Hosts and parasites form interacting populations that influence each other in multiple ways. Their dynamics can also be influenced by environmental and ecological factors. We studied host-parasite dynamics in a previously unexplored study system: side-blotched lizards and their micro-parasites.

Evidence of maternal effects on temperature preference in side-blotched lizards: implications for evolutionary response to climate change.

Natural populations respond to selection pressures like increasing local temperatures in many ways, including plasticity and adaptation. To predict the response of ectotherms like lizards to local temperature increase, it is essential to estimate phenotypic variation in and determine the heritability of temperature-related traits like average field body temperature (T b) and preferred temperature (T p). We measured T p of Uta stansburiana in a laboratory thermal gradient and assessed the contribution of sex, reproductive status and throat color genotype to phenotypic variation in T b of adult lizards.

Selection on the timing of adult emergence results in altered circadian clocks in fruit flies Drosophila melanogaster.

To investigate whether circadian clocks in fruit flies Drosophila melanogaster evolve as a consequence of selection on the timing of adult emergence, we raised four replicate populations each of early (early(1..4)) and late (late(1.

Non-ventral lateral neuron-based, non-PDF-mediated clocks control circadian egg-laying rhythm in Drosophila melanogaster.

The authors report the results of their study aimed at investigating the consequence of targeted ablation of ventral lateral neurons (LN(v)s--neurons regulating eclosion and locomotor activity rhythms) and genetic disruption of pigment-dispersing factor (PDF--an important output of circadian clocks) on the egg-laying rhythm of Drosophila melanogaster. The results clearly suggest that genetic ablation of LN(v)s and loss of function mutation of PDF abolish eclosion and locomotor activity rhythms, whereas the egg-laying rhythm continues unabated. Furthermore, the results also demonstrate that the period of egg-laying rhythm remains unchanged under different ambient temperatures and nutrition levels, suggesting that the egg-laying rhythm of D.

Evolution of temporal order in living organisms.

Circadian clocks are believed to have evolved in parallel with the geological history of the earth, and have since been fine-tuned under selection pressures imposed by cyclic factors in the environment. These clocks regulate a wide variety of behavioral and metabolic processes in many life forms. They enhance the fitness of organisms by improving their ability to efficiently anticipate periodic events in their external environments, especially periodic changes in light, temperature and humidity.

Possible role of eclosion rhythm in mediating the effects of light-dark environments on pre-adult development in Drosophila melanogaster.

Background: In insects, circadian clocks have been implicated in affecting life history traits such as pre-adult development time and adult lifespan. Studies on the period (per) mutants of Drosophila melanogaster, and laboratory-selected lines of Bactrocera cucurbitae suggested a close link between circadian clocks and development time. There is a possibility of clock genes having pleiotropic effects on clock period and pre-adult development time.

Multi-oscillatory control of eclosion and oviposition rhythms in Drosophila melanogaster: evidence from limits of entrainment studies.

The eclosion and oviposition rhythms of flies from a population of Drosophila melanogaster maintained under constant conditions of the laboratory were assayed under constant light (LL), constant darkness (DD), and light/dark (LD) cycles of 10:10h (T20), 12:12h (T24), and 14:14h (T28). The mean (+/- 95% confidence interval; CI) free-running period (tau) of the oviposition rhythm was 26.34 +/- 1.

Circadian clocks and life-history related traits: is pupation height affected by circadian organization in Drosophila melanogaster?

In D. melanogaster, the observation of greater pupation height under constant darkness than under constant light has been explained by the hypothesis that light has an inhibitory effect on larval wandering behaviour, preventing larvae from crawling higher up the walls of culture vials prior to pupation. If this is the only role of light in affecting pupation height, then various light : dark regimes would be predicted to yield pupation heights intermediate between those seen in constant light and constant darkness.

Glycogen synthase kinase 3beta as a likely target for the action of lithium on circadian clocks.

Although lithium is one of the most commonly used drugs in the prophylaxis and treatment of bipolar disorder, the mechanisms underlying its therapeutic action are still unclear. Together with its mood-stabilizing effects, lithium is also known to influence the circadian clocks of several organisms including man. Circadian rhythms are altered in patients with bipolar disorder, and it is believed that these rhythms may play an important role in disease mechanisms.

Entrainment of eclosion rhythm in Drosophila melanogaster populations reared for more than 700 generations in constant light environment.

In this paper, we report the results of our extensive study on eclosion rhythm of four independent populations of Drosophila melanogaster that were reared in constant light (LL) environment of the laboratory for more than 700 generations. The eclosion rhythm of these flies was assayed under LL, constant darkness (DD) and three periodic light-dark (LD) cycles (T20, T24, and T28). The percentage of vials from each population that exhibited circadian rhythm of eclosion in DD and in LL (intensity of approximately 100 lux) was about 90% and 18%, respectively.