Metrics details Abstract Geographic variation of phenotypic traits is common across species and is often associated with variation in environmental conditions. Here, we found larger bodies and larger size at maturity in a northward, lower latitude population of the crab Goniopsis cruentata, which inhabits a hotter, drier environment in comparison with a southward, higher latitude population. Furthermore, the juvenile male gonopods grow more relative to body size in the population characterized by maturation at a smaller size. In contrast, the female abdomen widens at a higher rate among the late maturing population. These results provide further evidence that local environmental conditions play a role in phenotypic variation between populations inhabiting different latitudes.
|Published (Last):||26 November 2018|
|PDF File Size:||18.59 Mb|
|ePub File Size:||16.42 Mb|
|Price:||Free* [*Free Regsitration Required]|
Metrics details Abstract Geographic variation of phenotypic traits is common across species and is often associated with variation in environmental conditions. Here, we found larger bodies and larger size at maturity in a northward, lower latitude population of the crab Goniopsis cruentata, which inhabits a hotter, drier environment in comparison with a southward, higher latitude population.
Furthermore, the juvenile male gonopods grow more relative to body size in the population characterized by maturation at a smaller size.
In contrast, the female abdomen widens at a higher rate among the late maturing population. These results provide further evidence that local environmental conditions play a role in phenotypic variation between populations inhabiting different latitudes.
Moreover, they also show that variation in size at maturity and body size can lead to divergent allometric patterns of sexual characteristics that can have a sex-specific response. This is often the case for species with broad geographic ranges in which latitudinal clines are observed. Latitudinal clines result in graded environmental conditions that can result in differences at either end of the spectrum, which is often demonstrated to affect biological traits in a myriad of species Monaco et al.
Indeed, several studies have shown that body size within a species tends to increase as the environmental temperature moves from warm to cold across a broad geographic scale Angilletta et al. While other factors e. For example, larger body sizes tend to be selected for under high desiccation risk because the smaller surface area in relation to body volume reduces vulnerability to desiccation Atkinson ; Gardner et al.
Body size virtually influences all physiological and fitness-related traits of an organism Kingsolver and Huey ; Gardner et al.
As such, its variation is likely to be associated with variations in other biological features. For instance, body size is often recognized as being highly correlated with size at maturity Stearns ; Hartnoll such that smaller animals often achieve maturity at smaller sizes Angilletta et al. Body size has also been associated with latitudinal variation and sexual maturity in many species of crustaceans in which larger bodies and larger size at maturity occur in higher latitudes, i.
This might suggest that a positive selective pressure exists for delayed maturation in cooler environments. These variations in body size and sexual maturity are likely to indirectly affect relative growth, the rate of development of one body part relative to the whole body Hartnoll This is suggested to be a response to stabilizing selection that allows males to copulate with a wide size range of females, in light of the close association between the morphology of the gonopods and the female genitalia Eberhard et al.
This relationship between sexual maturity and sexual characters can result in the growth of reproductive structures being influenced by the period of time an individual takes to reach a minimum reproductive size. Thus, it is reasonable to expect that the relative growth of reproductive structures relative to body size is greater when maturity is attained earlier.
We might expect that if body size and maturity vary between populations under different environmental conditions, the allometric growth of reproductive structures will as well. However, to our knowledge, studies that have attempted to test such variation are rare but see Hirose et al. Here, we study two populations of the tropical crab Goniopsis cruentata Latreille that inhabit mangroves in different latitudes along the coast of Brazil. These mangroves are subject to different temperatures, rainfall regimes, and evaporation rates, and both temperature and rainfall are known to influence reproduction of G.
In addition, because G. As a consequence, the biological traits of individuals inhabiting such environments might differ from their counterparts from cooler and more humid environments.
We tested whether such divergence occurs on the basis of body size, sexual maturity, and allometric growth of a primary and a secondary sexual character gonopod length and abdomen width in males and females, respectively.
Materials and methods Species and study localities Goniopsis cruentata is a crab species with a broad geographical distribution, occurring from Bermudas to Santa Catarina State, in the south of Brazil Melo This species inhabits virtually every microhabitat in mangrove ecosystems, but it is most often found wandering in the substratum above the tide level Melo The dry season starts in June and ends in January, and the rainy season starts in February and ends in May Folhes et al.
In Alagoas, the area of study is classified as a tropical humid region. The dry season starts in September and ends in February, and the rainy season starts in March and ends in August Calado and Sousa
Nigul At PR, a total of 30 animals were captured. Aquatic Toxicology 66, — A range of compounds present direct and indirect effects in DNA integrity of estuarine organisms: In laboratory, animals were processed for analysis within 12 h after sampling. Unionidae exposed singly and in combination to chemicals used in lawn care. Within one week, the cruenfata were gradually U thawed on ice, homogenized in ice cold potassium phosphate buffer 0. A simple technique for quantification of low C levels of DNA damage in individual cells.