What time of year do birds mate?

How does precipitation affect reproductive success in different species?

Reproductive success was greater in both of these species in years with more precipitation during the 7 months prior to breeding (long-term scale). However, the species differed in their reproductive response to weather during the breeding season (short-term).

Does timing of breeding influence reproduction in birds?

Introduction Timing of breeding is one of the most important factors influencing reproductive performance in birds. Individuals that breed early tend to produce larger clutches and more surviving offspring than individuals that breed later ( Lack 1968, Price and Liou 1989 ).

Does precipitation affect reproduction in arctic-nesting peregrine falcons?

Our results confirm that increased frequency of heavy precipitation can reduce reproductive output of arctic-nesting peregrine falcons directly (through exposure to cold, wet weather), and indirectly through the outbreak of black flies described here and elsewhere 31.

What are the most important environmental factors for animal reproduction?

Reproductive strategies vary with the genetic background of different animal species, and the most important environmental factors are those having greater influence on offspring survival. Many mammalian wild species inhabiting temperate zones adjust their reproductive season so that offspring births are concentrated during spring.

Why is the peregrine falcon population decreasing?

Severe declines in peregrine falcon numbers began in the 1950s [1]. These declines were linked to organochlorine pesticides that were put into use following World War II, and whose use peaked in the late 1950s-early 1960s [1].

Where do falcons nest in the Arctic?

The Arctic peregrine falcon (Falco peregrinus tundrius) is one of three subspecies of peregrine falcon [1]. The Arctic peregrine nests in tundra regions of Alaska, Canada (Yukon, Northwest Territories, Quebec, and possibly Labrador), and the ice-free perimeter of Greenland [1].

How does acidification affect the reproductive success of aquatic birds?

Acidification in aquatic habitats reduces the reproductive success of both piscivorous and non piscivorous birds, mainly by reducing the food supply. Piscivorous birds find some compensation in an increased transparency of the water, non piscivorous birds in less competition for invertebrate prey by fish.

What are the factors that affect animal reproduction?

Fertilization, production and other factors determine the way in which the animal reproduction is carried out. However, the basics can be categorized into these groups. Sexual reproduction in animals is characterized by requiring two individuals, one female and one male. The female will produce ovules formed by ovogenesis in her ovaries.

What are the environmental factors that determine the sex of organisms?

In some organisms, the environment determines the sexual phenotype of the individuals. Thus, some environmental factors, size of parent body or of egg, age of parent and temperature are found to determine the sex in following cases: (a) The sex of some reptiles may depend upon the temperature at which the individual develops.

Did female reproductive traits evolve to screen for mates?

Female reproductive traits may also sometimes evolve because of their screening effects on males. For example, the advantage of having offspring sired by males whose semen has particularly good abilities to resist a low pH might favour a further reduction in vaginal pH as a mate-screening device.

How does natural selection affect the female reproductive system?

Such female traits resulting from natural selection can also incidentally result in selection on males (e.g. favour the ability of sperm to survive at a low pH, or ability to produce seminal products that can raise the pH). Female reproductive traits may also sometimes evolve because of their screening effects on males.

What is the relationship between genetic variability and natural selection?

A species with a great deal of genetic variability is more likely to survive as a species in a changing environment than a species with limited variability. The theories of Charles Darwin still form the foundation for our understanding of natural selection. It is still widely upheld that natural selection is based on five factors:

How does acidification affect ecosystem activities in poorly-buffered freshwater?

Acidification in geologically-sensitive areas subject to appreciable acidic deposition has affected the activities of microbes, plants and animals in poorly-buffered freshwater ecosystems in Europe and N. America.

What is the difference between chromosomal sex determination and environmental sex determination?

In chromosomal sex determination–males and females have chromosomes that are distinguishable. In genic sex determination, sex is determined by genes, but the chromosomes of males and females are indistinguishable. In environmental sex determination, sex is determined fully or in part by environmental effects

How does food affect sexual selection in chickens?

Females can raise chicks on their own, freeing up males for the mating game. And in this food rich environment, sexual selection can become a more dominant evolutionary force. How food is distributed, whether it’s clustered or dispersed, can have a dramatic effect on what kinds of traits will be favored by sexual selection.

What are the patterns and processes of sexual selection?

The patterns and processes of sexual selection are best understood in the context of parental investment. Sexual selection occurs because there is a correlation between the gender of an individual and its parental investment in each offspring.

What determines the role of each gender during reproduction?

Nonetheless, the role of each gender during reproduction is determined by environmental factors (for example, by the distribution of resources) and vital cycles (if oestrus is synchronised or not).

What is the benefit of genetic variation within a species?

genetic variation in species. Natural selection CANNOT occur without… It ensures some organisms can survive an environmental change. What is the BEST describes the benefit of variation within a species? It happens over a long period of time.

What is the mechanism of natural selection?

Natural selection is one of the basic mechanisms of evolution, along with mutation, migration, and genetic drift. Darwin’s grand idea of evolution by natural selection is relatively simple but often misunderstood.

Which statement best explains the relationship between evolution and natural selection?

Evolution occurs by natural selection What statement best explains the relationship between evolution and natural selection? genetic variation in species. Natural selection CANNOT occur without… It ensures some organisms can survive an environmental change. What is the BEST describes the benefit of variation within a species?

How is sexual reproduction different in males and females?

Sexual reproduction often involves evolutionary differentiation of males and females. Females typically produce significantly fewer gametes (eggs) than males and invest heavily in each one. On the other hand, males produce many gametes (sperm) and invest little into each one.

How does sexual selection affect mate choice?

Male mate choice occurs most often when males are substantially involved in caring for their offspring, or when there is great variation in the quality of the females as mates within a population. If males are choosy about their mate, then over time females may evolve ornamentation or coloration that is subject to sexual selection.