Mating: Sexual selection
... − if they improve the males’ reproductive success by increasing matings − more than they harm reproductive success by increasing predation or other costs − two kinds of sexual selection: − intrasexual selection: selection that occurs due to differences in success at mating that result from interacti ...
... − if they improve the males’ reproductive success by increasing matings − more than they harm reproductive success by increasing predation or other costs − two kinds of sexual selection: − intrasexual selection: selection that occurs due to differences in success at mating that result from interacti ...
Model Details - Virtual Biology Lab
... on Caribbean islands and in South America. They are sexually dimorphic, with males being smaller than females, with much larger tails and fins. In Trinidad they live in small pools associated with mountain streams, some of which have pike cichlid (which prey on guppies) and some do not. Endler found ...
... on Caribbean islands and in South America. They are sexually dimorphic, with males being smaller than females, with much larger tails and fins. In Trinidad they live in small pools associated with mountain streams, some of which have pike cichlid (which prey on guppies) and some do not. Endler found ...
CRAYFISH DISSECTION
... move water over gills Move water over EGGS, transfer sperm (males) carry young/eggs (females) Propulsion during tailflips ...
... move water over gills Move water over EGGS, transfer sperm (males) carry young/eggs (females) Propulsion during tailflips ...
Sexual Selection and Reproductive Behaviour
... And this leads me to say a few words on what I call Sexual Selection. This depends, not on a struggle for existence, but on a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor, but few or no offspring. Sexual selection is, therefore, le ...
... And this leads me to say a few words on what I call Sexual Selection. This depends, not on a struggle for existence, but on a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor, but few or no offspring. Sexual selection is, therefore, le ...
4101SexualSelFemale
... less successful, but gives to them fewer descendants. The struggle falls, moreover, at a time of year when food is generally abundant, and perhaps the effect chiefly produced would be the modification of the secondary sexual characters, which are not related to the power of obtaining food, or to def ...
... less successful, but gives to them fewer descendants. The struggle falls, moreover, at a time of year when food is generally abundant, and perhaps the effect chiefly produced would be the modification of the secondary sexual characters, which are not related to the power of obtaining food, or to def ...
NS&SS
... The ratio of available males to available females NOT just the ratio of males to females -note: if a female is mated, she is no longer available for mating while males after being mated are still available for mating -as season progresses, skew towards more males than available females FEMALES ARE C ...
... The ratio of available males to available females NOT just the ratio of males to females -note: if a female is mated, she is no longer available for mating while males after being mated are still available for mating -as season progresses, skew towards more males than available females FEMALES ARE C ...
WHAT IS EVOLUTION? General definition: a change or modification
... -females prefer males with redder comb -females prefer dominant males -force copulations are common -female preferentially eject sperm low ranking males ...
... -females prefer males with redder comb -females prefer dominant males -force copulations are common -female preferentially eject sperm low ranking males ...
`Wingman` -- how buddies help alpha males get the girl
... explaining males' cooperative behavior. Following males across years showed that betas became alphas more often than other males, but not necessarily at the same territory where they were betas. Even when the local alpha slot was empty, some betas moved to be helpers elsewhere rather than take over ...
... explaining males' cooperative behavior. Following males across years showed that betas became alphas more often than other males, but not necessarily at the same territory where they were betas. Even when the local alpha slot was empty, some betas moved to be helpers elsewhere rather than take over ...
biol b242 sex and sexual selection
... Species compete, so a higher evolutionary rate can be adaptive for a species. May work against individual disadvantages for sex within populations: so a form of group selection. Asexual "cheats" might gain individual advantage and spread to fixation within their own species, but cannot spread to oth ...
... Species compete, so a higher evolutionary rate can be adaptive for a species. May work against individual disadvantages for sex within populations: so a form of group selection. Asexual "cheats" might gain individual advantage and spread to fixation within their own species, but cannot spread to oth ...
11 Big Fish, Little Fish
... must receive eggs directly from a female or actively pick up eggs after a female discharges them.) Even in species that furnish no parental care, eggs must be provided with nutri ment, while sperm is little more than naked DNA with a delivery system. Larger eggs require more room and a big ger bod ...
... must receive eggs directly from a female or actively pick up eggs after a female discharges them.) Even in species that furnish no parental care, eggs must be provided with nutri ment, while sperm is little more than naked DNA with a delivery system. Larger eggs require more room and a big ger bod ...
Evolution of sex
... offspring they can sire. Females, however, have a much greater biological investment in their offspring (e.g. egg ...
... offspring they can sire. Females, however, have a much greater biological investment in their offspring (e.g. egg ...
A) The evolution of sex
... are? May work against individual disadvantages for sex within populations: so group selection. Asexual "cheats" gain individual advantage, spread to fixation within species, not to other species. Asexual species do exist (e.g. dandelions). Why do they not take over? If other species evolving/adaptin ...
... are? May work against individual disadvantages for sex within populations: so group selection. Asexual "cheats" gain individual advantage, spread to fixation within species, not to other species. Asexual species do exist (e.g. dandelions). Why do they not take over? If other species evolving/adaptin ...
Chapter 11
... If male reproductive success is limited by pollinator visits then male pollen from yellow-flowered plants should have gotten ¾ of reproductive success, since they received ¾ of the visits. ¾ of the seeds did produce yellow flowered plants. So male success was directly related to the access to pollin ...
... If male reproductive success is limited by pollinator visits then male pollen from yellow-flowered plants should have gotten ¾ of reproductive success, since they received ¾ of the visits. ¾ of the seeds did produce yellow flowered plants. So male success was directly related to the access to pollin ...
The PowerPoint
... Most animals restrict their sexual activity to narrowly defined periods of time, while we have sex all month and all year round. We are very sexy animals -- maybe the sexiest of all animals. We do not limit sexual activity to distinct breeding seasons or special periods of receptivity (like being i ...
... Most animals restrict their sexual activity to narrowly defined periods of time, while we have sex all month and all year round. We are very sexy animals -- maybe the sexiest of all animals. We do not limit sexual activity to distinct breeding seasons or special periods of receptivity (like being i ...
Evolution of Sex, Part 1.
... w/increased fitness. But the males aren’t stupid! When no females are present they don’t go anywhere near a ...
... w/increased fitness. But the males aren’t stupid! When no females are present they don’t go anywhere near a ...
lecture 09 - sexual selection - Cal State LA
... Now, consider a population w/ 10 male fish and one female: Only one male can ultimately father her offspring Female will (1) choose her mate, or (2) mate with the male who can fend off all his competitors Female reproductive success is not limited by access to mates ...
... Now, consider a population w/ 10 male fish and one female: Only one male can ultimately father her offspring Female will (1) choose her mate, or (2) mate with the male who can fend off all his competitors Female reproductive success is not limited by access to mates ...
a WORD version of the handout
... One feature of many species that is not easily explained by natural selection is sexual dimorphism. = females & males differ phenotypically. Examples: 1. Male cardinals are bright red, while females are drab. 2. Male peacocks have massive tails and are brightly colored compared to females. Why do th ...
... One feature of many species that is not easily explained by natural selection is sexual dimorphism. = females & males differ phenotypically. Examples: 1. Male cardinals are bright red, while females are drab. 2. Male peacocks have massive tails and are brightly colored compared to females. Why do th ...
2013_Cryan_Sexual_Selection copy
... reproductive success, males will compete with other males for mating opportunities Intersexual Selection (Female Choice): If female reproductive success is not limited by access to males, then females will be selective about which males they mate with in order to maximize the quality of the male’s ...
... reproductive success, males will compete with other males for mating opportunities Intersexual Selection (Female Choice): If female reproductive success is not limited by access to males, then females will be selective about which males they mate with in order to maximize the quality of the male’s ...
Sexual Selection II - University of Arizona | Ecology and Evolutionary
... So, females INVEST more in gametes, and have more investment in each offspring compared to males; Asymmetry in sexual reproduction established… What effects does this have on mating behavior? ...
... So, females INVEST more in gametes, and have more investment in each offspring compared to males; Asymmetry in sexual reproduction established… What effects does this have on mating behavior? ...
Sexual Selection
... A special form of natural selection explains the evolution of these puzzling traits ...
... A special form of natural selection explains the evolution of these puzzling traits ...
Sexual conflict
Sexual conflict or sexual antagonism occurs when the two sexes have conflicting optimal fitness strategies concerning reproduction, particularly over the mode and frequency of mating, potentially leading to an evolutionary arms race between males and females. For instance, males may benefit from multiple matings, while multiple matings may harm or endanger females. The development of an evolutionary arms race can also be seen in the chase-away sexual selection model, which places inter-sexual conflicts in the context of secondary sexual characteristic evolution, sensory exploitation, and female resistance. According to chase-away selection, continuous sexual conflict creates an environment in which mating frequency and male secondary sexual trait development are somewhat in step with the female’s degree of resistance. It has primarily been studied in animals, though it can in principle apply to any sexually reproducing organism, such as plants and fungi.Sexual conflict/antagonism can be in two forms:Interlocus sexual conflict is the interaction of a set of antagonistic alleles at one or more loci in males and females. An example is conflict over mating rates. Males frequently have a higher optimal mating rate than females because in most animal species, they invest fewer resources in offspring than their female counterparts. Therefore, males have numerous adaptations to induce females to mate with them. Another well-documented example of inter-locus sexual conflict is the seminal fluid of Drosophila melanogaster, which up-regulates females' egg-laying rate and reduces her desire to re-mate with another male (serving the male's interests), but also shortens the female's lifespan reducing her fitness.Intralocus sexual conflict This kind of conflict represents a tug of war between natural selection on both sexes and sexual selection on one sex. For example, the bill color in Zebra finches etc. Ornamentation could be costly to produce, it is important in mate choice but also makes an individual vulnerable to predators, the alleles for such phenotypic traits are under antagonistic selection and this conflict is resolved via elaborate sexual dimorphism thus maintaining sexually antagonistic alleles in the population. Evidence indicates that intralocus conflict may be an important constraint in the evolution of many traits.Sexual conflict may lead to antagonistic co-evolution, in which one sex (usually male) evolves a favorable trait that is offset by a countering trait in the other sex. Similarly, interlocus sexual conflict can be the result of what is called a perpetual cycle. The perpetual cycle begins with the traits that favor male reproductive competition, which eventually manifests into male persistence. These favorable traits will cause a reduction in the fitness of females due to their persistence. Following this event, females may develop a counter-adaptation, that is, a favorable trait that reduces the direct costs implemented by males. This is known as female resistance. After this event, females' fitness depression decreases, and the cycle starts again. Interlocus sexual conflict reflects interactions among mates to achieve their optimal fitness strategies and can be explained through evolutionary concepts.Sensory exploitation by males is one mechanism that involves males attempting to overcome female reluctance. It can result in chase-away selection, which then leads to a co-evolutionary arms race. There are also other mechanisms involved in sexual conflict such as traumatic insemination, forced copulation, penis fencing, love darts and others.Female resistance traditionally includes reducing negative effects to mechanisms implemented by males, but outside the norm may include sexual cannibalism, increased fitness in females on offspring and increased aggression to males.Animal species that are not in a state of sexual conflict are more likely to be in sync to the male dominance hierarchy as the females are more docile in these organizations such as wolves, common rabbits and crocodiles. Others, such as spiders, ants and orcas are female-dominated. Some regard sexual conflict as a subset of sexual selection (which was traditionally regarded as mutualistic), while others suggest it is a separate evolutionary phenomenon.