DNA links male, female butterfly thought to be distinct species

Date: July 27, 2017

Source: Florida Museum of Natural History

Summary: Researchers recently discovered what was thought to be a distinct species of butterfly is actually the female of a species known to science for more than a century.An international team of nine butterfly researchers from the U.S., Brazil, the U.K., Peru and Germany used DNA sequence data to associate the female sunburst cerulean-satyr, or Caeruleuptychia helios, an Amazonian brush-footed butterfly, with its male counterpart.

Males and females of this group look dramatically different from each other, a phenomenon known as sexual dimorphism, and the species was named and described in 1911 based on the brilliantly iridescent blue males. Rarer than the male, the brown female was considered another species and was recently named and placed in a different genus, Magneuptychia keltoumae.

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Seal evolution: Sexual dimorphism in pinnipeds arose around 27 million years ago as climate changed

Date:

February 19, 2014

Source:

Canadian Museum of Nature

Summary:

Modern pinnipeds (the group that includes seals, sea lions and walruses) show a range of sexual dimorphism (large differences in size between males and females) and mating systems that span the extremes of modern mammals. A new study using the fossil record establishes that sexual dimorphism in pinnipeds, marked by harem-like behavior, arose around 27 million years ago in association with changing climatic conditions. Taken in the modern context of climate change, this research has major implications for the future of the species.

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Sexual Dimorphism In Relative Digit Length In Lizards and Frogs

Posted on January 23, 2013 by Jonathan Losos, Anoleannals.org

In recent years, a quirky area of research has developed in which researchers measure the length of the second and fourth digits on the hand and foot, calculate the ratio (2d:4d) and then compare this ratio between the sexes. Surprisingly, in many species there are consistent differences between males and females. In mammals, that ratio is smaller for males, whereas in birds, the opposite occurs. But few studies have looked at the other vertebrate classes.

With this in mind, Direnzo and Stynoski recently calculated digit ratios for several common Costa Rica anoles and frogs. The abstract of their paper, published in Anatomical Record last year, tells the story:

“It is now well documented that androgen and estrogen signaling during early development cause a sexual dimorphism in second-to-fourth digit length ratio (2D:4D). It is also well documented that males of mammalian species have a smaller 2D:4D than females. Although there are discrepancies among 2D:4D studies in birds, the consensus is that birds exhibit the opposite pattern with males having a larger 2D:4D than females. The literature currently lacks substantial information regarding the phylogenetic pattern of this trait in amphibians and reptiles. In this study, we examined 2D:4D in two species of frogs (Oophaga pumilio and Craugastor bransfordii) and two species of lizards (Anolis humilis and Anolis limifrons) to determine the existence and the pattern of the sexual dimorphism. Male O. pumilio and C. bransfordii displayed larger 2D:4D than females in at least one of their two forelimbs. Male A. humilis had larger 2D:4D than females in both hindlimbs, but smaller 2D:4D than females in both forelimbs. Male A. limifrons may also have smaller 2D:4D than females in the right forelimb. Finally, digit ratios were sometimes positively related to body length, suggesting allometric growth. Overall, our results support the existence of the 2D:4D sexual dimorphism in amphibians and lizards and add to the knowledge of 2D:4D trait patterning among tetrapods.

European Dung-Fly Females All Aflutter for Large Males

ScienceDaily (Apr. 13, 2012) — European dung fly females prefer large males, making them the driving selective force behind the rare phenomenon in insects of large males and small females. This is what evolutionary ecologists from the University of Zurich discovered when they compared North American and European dung flies, which not only differ in sexual size dimorphism (SSD), but also in their mating behavior.

European and North American black scavenger flies -- also called dung flies as their larvae develop in the feces of vertebrates and thus break them down -- belong to the same species. Nevertheless, they strongly differ in mating behavior and SSD. North American dung fly females are larger than males, the usual dimorphism in insects. European dung flies, however, are more unusual with males being considerably larger than females. In evolutionary biology, sexual selection for large males can be explained if they can reproduce more successfully than smaller ones, either because females prefer larger males or because the latter prevail more often in the competition for mates with other males. Evolutionary ecologists from the University of Zurich showed that female preference for large males is far greater in European fly populations than in their North American counterparts, which explains the different SSD.

Continued:  http://www.sciencedaily.com/releases/2012/04/120413101112.htm