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Reduction of a visually mediated association preference in the Cave molly (
Michael Tobler(1,2), Heike Burmeister(3), Ingo Schlup (2,3), Martin Plath
Poecilia mexicana, Poeciliidae, Teleostei) |
2006
Several studies have reported on the persistence of visually mediated social preferences, such as preferences of females to associate with certain types of males, in an eyed cave fish, the Cave molly (Poecilia mexicana). However, so far most studies have examined preferences which are apparently currently under selection, i.e., the preferences are expressed also in darkness. In this paper we examined female preferences for (1) conspecific females and (2) males without a parasite-induced color change (black spot disease, BSD). In both cases, selection on the persistence of the preference is not apparent. As predicted, surface-dwelling females preferred conspecific over heterospecific females, but this preference was not found in the Cave molly. However, we found no evidence for female preferences relative to BSD-infection of males. We discuss that BSD-resistance probably has a low indicator
value, so that this trait appears to be of minor importance for female mate choice even in surface-dwelling mollies.
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Genetics of Platypoecilus III. Inheritance of sex and crossing over of the sex chromosomes in the platyfish
MYRON GORDON
February 5, 1937
GENETIC evidence of crossing over between the sex G chromosomes of heterogametic individuals (XU males and WZ females) is so rare in animals as to give special significance to additional data on this occurrence. AIDA (1921) has shown in the Japanese ricefield killifish, Aplocheilus, that the X and Y chromosomes of the male occasionally cross over. In 1930 he presented additional data on this, together with some interesting data involving aberrant sex ratios, which he interpreted as due to nondisjunction.
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Published Paper: Body shape & size divergence of Poecilia vivipara in lagoons, NEVES, F.M. 2003 |
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Body shape and size divergence among populations of Poecilia vivipara in coastal lagoons of south-eastern Brazil
F. M. NEVES & L. R. MONTEIRO
2003
Geometric shape analyses were used to study body shape and size variation among populations
of the livebearing fish Poecilia vivipara inhabiting the recently formed coastal lagoons of
Grussaı´ and Iquipari in Northern Rio de Janeiro State, Brazil. The largest components of
morphological variation among females were between different habitats in the same lagoon,
whereas for males there were larger differences between lagoons than between habitats.
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Published Paper: Variation in male genitalia in Brachyraphis episcopi, JENNIONS, M.D. 2002 |
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Geographical variation in male genitalia in Brachyrhaphis episcopi (Poeciliidae): is it sexually or naturally selected?
Jennions, M. D. and Kelly, C. D. 2002. Geographical variation in male genitalia in
Brachyrhaphis episcopi (Poeciliidae): is it sexually or naturally selected? – Oikos 97:
79–86.
Male poeciliid fishes inseminate females using an intromittent organ called the gonopodium. Here we report on natural variation in gonopodium size both within and between 12 populations of the freshwater fish Brachyrhaphis episcopi (Poeciliidae) in Panama. We show that males from sites with more predatory fish species have, on average, a relatively longer gonopodium than males inhabiting sites with fewer predatory fish. Gonopodium length was not correlated with the site-specific adult sex ratio and the average sex ratio was more strongly female biased at sites with more predatory fish. The gonopodium exhibited lower phenotypic variance than the average for sexually selected traits and it generally showed negative allometry. Our results are similar to those reported for the guppy Poecilia reticulata.
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Published Paper: Reproductive cycle of Jenynsia multidentata, GARCIA, A.M. 2004 |
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Reproductive cycle and spatiotemporal variation in abundance of the one-sided livebearer Jenynsia multidentata, in Patos Lagoon, Brazil
Alexandre M. Garcia, João P. Vieira, Kirk O. Winemiller & Marcelo B. Raseira
2004
Jenynsia multidentata is an important component of the fish assemblage of the Patos Lagoon estuary in southern South Brazil. In order to investigate its reproductive cycle and abundance patterns, standardized sampling was conducted over large spatial (marine, estuary and lagoon) and temporal (1996–2003) scales. Both females and males were significantly more abundant during summer (December–March) than winter (June–August).
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