Can aposematic signals evolve by gradual change?

Aposematic species, which signal conspicuously of their unprofitability to predators, have puzzled evolutionary biologists for over a century1,2. Although conspicuousness of unpalatable prey improves avoidance learning by predators3,4,5, it also involves an evolutionary paradox: with increasing detectability4,6,7,8 the deviant aposematic prey would suffer high predation initially from naive predators. Here we test a neglected idea7,8,9,10,11 that aposematic coloration may evolve by gradual change rather than by major mutations. Weak signals did not suffer high initial predation, but predators (great tits, Parus major) did not learn to separate them from cryptic palatable prey. Furthermore, …

Kestävän bioenergiatulevaisuuden rakentaminen : Osa 2, Bioenergiaopetus Keski-Suomessa bioenergiakoulutuksen resurssit

Kestävän bioenergiatulevaisuuden rakentaminen : Osa 1, Keski-Suomen bioenergiakoulutuksen historia ja tulevaisuus bioenergiakoulutuksen resurssit

Decreased sexual signalling reveals reduced viability in small populations of the drumming wolf spider Hygrolycosa rubrofasciata.

One of the important goals in conservation biology is to determine reliable indicators of population viability. Sexual traits have been suggested to indicate population extinction risk, because they may be related to viability through condition dependence. Moreover, condition-dependent sexual traits may be more sensitive indicators of population viability than early life-history traits, because deleterious fitness effects of inbreeding tend to be expressed mainly at the end of the species' life history. However, empirical evidence of the significance of sexual behaviour for population viability is missing. In this study, we examined two male sexual traits and survival in 39 different-sized …

Kestävän bioenergiatulevaisuuden rakentaminen : Osa 3, Keski-Suomen bioenergiakoulutuksen kehittäminen bioenergiakoulutuksen resurssit

Fluctuating asymmetry and sexual performance in the drumming wolf spider Hygrolycosa rubrofasciata

Recently, there has been much interest in estimating fluctuating asymmetry (FA) of morphological traits as a short-cut measure of individual quality. FA deals with small differences around the symmetry value of zero. Thus, measurement error is often relatively large. However, repeated measurements. and large sample sizes allow reliable estimates of FA that can be corrected for errors. The purpose of this study was two-fold: at the biological level, we examined with a large sample size (N = 804) whether pedipalp FA could be used as a short-cut measure, of individual quality in the wolf spider Hygrolycosa rubrofasciata. This was done by estimating how strongly FA correlates with male sexual p…