Chapter 5 Flashcards
What is the difference between weather and climate in terms of temporal variation?
Whereas weather refers to short-term changes in the atmosphere, climate describes what the weather is like over a long period of time in a specific area. Different regions can have different climates. Weather in New York can vary over the interval of hours from cold to hot, while climate changes in a long period of time in the atmosphere. Climate varies seasons of the year. NY climate would be humid subtropical climate
How could spatial heterogeneity be perceived by an organism as temporal heterogeneity?
Moving through environments that vary in space, an individual experiences environmental variation as a sequence in time. In other words, a moving individual perceives spatial variation as temporal variation. The faster an individual moves and the smaller the scale of spatial variation, the more quickly the individual encounters new environmental conditions and the shorter the temporal scale of the variation.
Why do we have to consider the mean fitness across all environments when evaluating whether evolving a phenotypically plastic genotype will be favored over a nonplastic genotype?
Plastic genotype will only be advantageous when the variation in space and time occurs frequently. If the environment changes a lot then we will see the mean fitness of the plastic genotype will be higher. We will also see that the non-plastic genotype do good in one environment and not the other so the mean fitness will be less. But if the environment does not change the nonplastic genotype will be favored since its mean fitness will be higher. Plastic genotype does well in both environments but not as good as non-plastic genotype in the slow changing environment.
How would the presence of unreliable environmental cues affect the evolution of phenotypically plastic responses to environmental variation?
-The presence of unreliable environmental cues would speed up natural selection, those with poor environmental cues would die out due to not sensing threats like predation. The species with good cues will live on and have more offspring and spread their genes. Gray tree frog tadpoles produce a phenotype that allows fast escape when predators are present and fast growth when predators are absent. The cost of this phenotype is slower growth of tail.
-The fitness advantage of phenotypic plasticity occurs whenever environmental variation in space or time occurs frequently. If environmental conditions change frequently, then the phenotype favored by natural selection also changes frequently, and this gives the plastic genotype a higher average fitness than the nonplastic genotype.
-environmental cues can take many forms, including smells, sights, sounds, and changes in abiotic conditions. When a species has multiple possible environmental cues that it could use, we might expect the species to evolve to use the most reliable cue. When organisms have very reliable cues, they can more accurately produce a phenotype that is well suited to the environment.
Would the frequency of experiencing predator versus no- predator environments affect the evolution of phenotypically plastic traits?
yes , in plastic phenotypes the organisms develop a phenotype in response to a predator like improved chances of escape ex. Tadpoles swimming away faster. If no predators tadpoles likely would not need to swim away fast and the evolution would be slower. . In environments with predators, the tadpoles produce a phenotype that is well suited to escaping detection and capture. In environments that are free of predators, the tadpoles produce a phenotype that is well suited for faster growth.
If predators reduce prey abundance to very low levels, how might variable predator environments affect the evolution of flexible mating strategies?
If predators reduce prey abundance to very low levels, then the prey might have to find more flexible mating strategies. Like being able to asexual produce. Ex. snails When potential mates are abundant, a snail will typically mate with another individual, but when potential mates are rare, it can fertilize its eggs with its own sperm. Fertilizing own eggs might cause a disadvantage (less variable traits) but better than nothing.
If a plant can improve its ability to obtain water by growing more roots, why shouldn’t the plant always grow more roots?
Having more roots is not always a phenotypic advantage because it comes at the cost of photosynthesis. When water was abundant, the plants devoted more energy to the growth of shoots, which function primarily to photosynthesize. When water was scarce, the plants devoted more energy to the growth of roots, which expanded their ability to capture what little water was available. Given that these plants experience variation in water availability, it is clear that no single allocation strategy would be as beneficial as the phenotypically plastic strategy that they exhibit.
How could you experimentally determine whether migrating birds use length of the day or temperature as an environmental cue for migration?
Monitor bird migration.. Trigger both cues for time of day and temperature. maybe change temperature to see if migration increases or decreases. Increase or decrease daylight see what happens. Keep temp constant etc.
What is the relationship between correlation and causation?
Correlation does not always mean causation. Just cuz u see increase in A and increase in B does not mean that the increase in A caused increase in B. The two events can be independent of each other. Causation indicates that one event is the result of the occurrence of the other event, but correlation it can be independent of each other
When determining whether to feed on small, medium, or large prey, why should predators evaluate the energy obtained from each prey item, the abundance of each prey item, and the handling time of each prey item?
Predators need to find what’s optimal for them. Large prey give more food more energy but it takes longer to hunt (handling time). It is best to go for the abundant species because it will take the least amount of time to find (most efficient). If abundant they should also go after the species that gives them the most energy
For example, the predator should always eat the prey species that provides the highest energy benefit; if this prey is abundant, it is the only prey that the predator should consume. This strategy maximizes the animal’s energy gain. However, if this highest-energy prey is rare and the predator’s energy needs are not met, the animal should include less profitable items in its diet. Prey species of very low energy value should never be included in the diet unless all higher-energy prey are scarce. Ex. The coyotes always consumed the jackrabbits regardless of their abundance. However, when jackrabbits became less abundant, the coyotes increased their consumption of cottontail rabbits and voles.
