Essay Example on Created light mimicked the natural light conditions of both Species









Recent findings The general experimental setup consisted of two way mate choice experiments Gravid females were exposed to one male per species on both sides of a fish tank Two different settings were used One in which females and males were completely isolated both chemically and partly visually In the second setup visual barriers where absent and chemical communication was possible These setups provided the basis for the following findings Wright et al tested if rearing light conditions affect female preference Created light mimicked the natural light conditions of both species The experiment showed that rearing light conditions so the visual environment significantly affected female preference for courtship behaviour of both species As expected females reared under shallow water light conditions preferred P pundamilia males In contrast to this result females reared under deep water light conditions did not show any preference These findings were based on typical courtship behaviour observations of both males quiver and lateral display and females which normally move to or either away from the male Possible effects of test light female species and male size were nonsignificant They proposed two possible explanations First the used light conditions induce the expression of certain pigments like opsin which cause either red of blue colourations The second explanation involves the exposure of females to certain male phenotypes which could cause imprinting of colour preferences Beside examining female preferences they also explored the extent in which these species showed assortative preference 

They reviewed all models and excluded results of hybrid females These results showed strong interaction between female species and rearing light conditions in terms of lateral display and quiver behaviour This indicates that both species respond stronger to conspecific males when reared under their natural light conditions compared to unnatural light conditions P pundamilia females reared in shallow water conditions preferred conspecific males but when reared under deep water conditions they did not P nyererei females both reared in deep and shallow conditions did not show any preference Pooling and re categorizing light deep shallow and natural unnatural conditions showed that the rearing environment significantly affects the assortative preference in terms of quiver behaviour but not lateral display These results show that heterogeneity in their local habitat is linked to female preferences and eventually reproductive isolation This means that changes in local conditions like climate change or migration can influence the reproduction and thus survival of these species Even though their female preference experiments do show clear result the overall repeatability was low Lower repeatability was observed at P nyererei females compared to P pundamilia and hybrid females but this was not caused due to the two different light conditions either due to their experimental setup No difference in female preference between the earlier mentioned setups was observed Even though they did not observe any significant setup effect they did observe more active females and positive responses to lateral male display in setup 2 which allows chemical exchange and visual communication 

Compared to lateral display behaviour less positive responses to male quiver behaviour were observed Separate female preference analysis between setups showed increased fish activity in setup 2 but no setup effect on preference scores These results suggest that female preference is not affected by chemical communication In addition they examined the effect of test light on fish activity They showed that test light did not affect fish activity in terms of female response to males and female activity Females did somewhat more respond to male lateral display in deep light conditions than for quiver behaviour Compared to P pundamilia females P nyererei females responded more to male quivers under shallow water light conditions In general hybrid females were more active compared to P nyererei and P pundamilia and no difference between these species was observed Male courtship activity was similar in both shallow and deep light conditions However male courtship behaviour of P pundamilia was more frequently observed under deep light conditions whereas frequencies of P nyererei were similar under both conditions Discussion and future developments Rearing both species including their hybrids under various light conditions showed that the visual environment during development affects female preference Two explanations were proposed related to expression of certain pigments like opsin and imprinting for male colour preferences Previous studies showed increased expression of opsin concentration in fish as response to changes in visual environment

 This relation is not straightforward as it depends on more complex interactions between genotypes rearing environment and test environment More research focused on pigment expression under these light conditions in pundamilia species is needed Even though it is shown that perceptual variation affects female preference we cannot conclude that it completely determines female preference In that case we would have seen stronger interactions between test light and rearing light conditions Also even though imprinting for male colourations is unlikely future research should focus on individually housing and controlling the fish prior to similar experiments Furthermore even though species assortative preferences were significant the results were surprisingly weak This might be due to the used light conditions Specific light spectra were used to mimic natural conditions but these differ strongly compared to those used in previous studies Another explanation could be due to filial imprinting as fry was removed 5 6 days after birth and housed in family groups This way differs from the natural maternal care mouth brood which allows imprinting of their parent phenotype Another last explanation could be due to selective survival which is possible as the used individuals originated from wild caught individuals that might have caused strong genetic variation and thus a nonrandom test population

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