The song nuclei of the male zebra finch (Poephila guttata) contain larger neurons than those of the female. This gender difference arises after hatching as a result of cell atrophy in the female and cell growth in the male. Implantation of estrogen in female chicks induces masculine differentiation of neurons in their song nuclei. The effects of estrogen on neuron size decline steeply after pos...

Spaced practice affects learning efficiency in humans and other animals. However, it is not well understood how spaced practice contributes to learning during development. Here, we show the behavioral significance of singing frequency in song development in a songbird, the zebra finch. Songbirds learn a complex song pattern by trial-and-error vocalizations as self-motivated practice, which is e...

Learned bird songs are often characterized by a high degree of variation between individuals and sometimes between populations, while at the same time maintaining species specificity. The evolution of such songs depends on the balance between plasticity and constraints. Captive populations provide an opportunity to examine signal variation and differentiation in detail, so we analyzed adult mal...

A juvenile male zebra finch, Taeniopygia guttata, kept singly with its father develops a fairly complete imitation of the father's song. The imitation is less complete when other male siblings are present, possibly because as imitation commences, model abundance increases. Here we examine the consequences of allowing more or less access to a song model. Young males heard a brief song playback w...

Fitness trade-offs between environments are central to the evolution of biodiversity. Although transplant studies often document fitness trade-offs consistent with local adaptation (LA), many have also found an advantage of foreign genotypes (foreign advantage (FA)). Understanding the mechanisms driving the magnitude and distribution of fitness variation requires comparative approaches that tes...

Abstract Cladocerans are a diverse group of species that show rapid responses to changes in environmental conditions. This adaptive capacity has important implications for egg production and life cycle, especially transitory environments such as temporary waterbodies. The present study investigated the history Alona gutatta Sars, 1862 (Crustacea, Cladocera), an abundant frequent from high-altit...

The zebra finch Taeniopygia guttata castanotis is a songbird commonly used in the laboratory, particularly for studies of vocal learning, neurobiology, and physiology. Within the laboratory, it is important to adopt careful husbandry practices that allow for normal development of the birds. For example, their song is a learned trait, passed culturally from adult males to juveniles, and thus its...

To date, the forcipules have played almost no role in determining the systematics of scutigeromorph centipedes though in his 1974 review of taxonomic characters Markus Würmli suggested some potentially informative variation might be found in these structures. Geometric morphometric analyses were used to evaluate Würmli's suggestion, specifically to determine whether the shape of the forcipular ...

Experimental evidence suggests that females would prefer males with better cognitive abilities as mates. However, little is known about the traits reflecting enhanced cognitive skills on which females might base their mate-choice decisions. In particular, it has been suggested that male foraging performance could be used as an indicator of cognitive capacity, but convincing evidence for this hy...

Across a range of species including humans, personality traits, or differences in behaviour between individuals that are consistent over time, have been demonstrated. However, few studies have measured whether these consistent differences are evident in very young animals, and whether they persist over an individual's entire lifespan. Here we investigated the begging behaviour of very young cro...