Exam 1 Flashcards
Describe FITNESS in terms of an individual’s effect on its species’ gene pool.
Fitness = A measure of an individual’s relative reproductive success.
(sending genes into the future)
How does natural selection work?
- Species are related by common ancestry.
- Characteristics of a species can be modified from generation to generation. Darwin called this decent with modification.
Evolution by natural selection occurs whenever two conditions are met. - Individuals within a population vary in characteristics that are HERITABLE (traits can be passed on to offspring.)
- In a particular environment, certain versions of these heritable traits help individuals survive OR reproduce more than do other versions.
If certain HERITABLE traits lead to increases success in producing offspring, then those traits become MORE COMMON in the population over time.
- The population’s characteristics change as a result of Natural Selection acting on individuals.
- -> Natural selection acts on individual.
- -> Evolutionary change occurs in population.
Explain DIRECT FITNESS
Direct fitness = is derived from an individual’s own offspring (reproductive output) Parents can increase their direct fitness by spending resources to ensure the welfare of their offspring.(influence)
Direct fitness pass on copies of DNA from generation to generation.
Explain INDIRECT FITNESS
Indirect fitness = is derived from helping relatives reproduce and care for offsprings. This allows the relative to produce more offsprings than they could produce on their own.
Indirect fitness is achieved when non-descendants relatives reproduce.
Explain INCLUSIVE FITNESS
Inclusive fitness = Hamilton’s rule suggests that an individual can pass on their alleles to the next generation not only by having their own offspring, but also by helping close-relatives produce more offspring.
Inclusive fitness is the combination of both Direct and Indirect fitness components.
Explain KIN SELECTION
Kin selection = is natural selection that acts through benefits to relatives (preferably close relatives, such as offsprings) at the expense of the individual.
Describe the effects on a population of some abiotic factor which can vary from too-low to too-high values; include the concepts of optimal range, zone(s) of physiological stress, and zone(s) of intolerance. . . Be familiar with the bell curve (often called the survival curve) presented in lecture - be able to reproduce it, and explain in detail what it shows.
No one species has the capability to survive the full range of environmental conditions present on Earth. Temperature is particularly important in determining the distribution and abundance of any particular species because temperature has a big impact on the physiology of organisms, and organisms are limited in their ability to regulate their own temperatures.
Peter Panyon in mentioned living things are required to maintain a regulated temperature. 98.2°F is the optimal temperature for enzymes to catalyze the chemicals that keep you alive.
Fitness trade-off --> no enzyme can function well in both extremely high temperatures and extremely low temperatures. Organisms tend to be adapted to a limited set of physical conditions or abiotic factors. Every organism has specific range of tolerance of abiotic conditions.
#example: graph demonstrates the optimal range of a species of butterflies in relation to the environmental gradient (temperature, moisture, altitude, sunlight, vegetation). In zones of physiological stress the butterfly is shown infrequently, if certain individuals of this species can tolerate abnormal environmental gradients in the zone of physiological stress, they can pass down heritable genes that allow them to tolerate these abnormal environmental gradients (evolution by natural selection). The zone of intolerance is the region where the abiotic factors are either too low or too high for the particular species to survive. therefore, the species will be absent in environmental conditions where it is physiologically impossible to survive.
However, keep in mind it is never just one factor to limit the abundance and distribution of a species.
Define LIMITING FACTOR, give some examples, explain how this relates to niche.
A limiting factor is any condition that restricts the distribution or abundance of a species.
Example: the butterfly survival curve demonstrates the environmental gradient limiting factor of the butterfly species in the graph. For example, if the environmental gradient is temperature, the butterfly species distribution and abundance is restricted by too high or too low temperatures.
An organism can only have it’s niche where the organisms limiting factor allows it to be.
Define niche; distinguish between niche and habitat; distinguish between fundamental niche and realized niche; define vacant niche.
A niche is a set of conditions that have to come true (role, lifestyle, uses, interactions)
A niche is not a place. “Habitat” is the place.
Habitat is an environmental or ecological area that is inhabited by a particular species. Niche is the resources or conditions in which a species require in order to survive.
Fundamental niche - is the total theoretical range of environmental conditions that a species can tolerate. Usually it’s the range that overlaps with the stronger competitor.
Realized Niche - is the portion of the fundamental niche that a species actually occupies, given limiting factors such as competition with other species. The weaker competitor has to adapt in order to survive.
Define COMPETITION. What does COMPETITIVE EXCLUSION” mean?
Competition is the attempted utilization of a limited resource.
Two species can share the same habitat, but not the same niche due to the competitive exclusion principle in which disallows coexisting niches.
Explain how the act of competing affects fitness, and explain why is this so.
The act of competing reduces the fitness of the competing individuals.
Competition cost you time and energy that could be used to reproduce.
Winners of competitions end up with more fitness than the loser, but less than what they could have had if they did not spend so much energy competing in the first place.
What is OPTIMAL FORAGING THEORY? Give examples that explain how it works.
- Feeding has energy costs and energy gains.
- Predators tend to choose prey that maximize their net energy gain.
- The trick to take in enough energy to satisfy all of the costs and still have enough left over to achieve fitness.
- An individual that maximizes it’s energy “profit” is likely to achieve more fitness than one that does not.
Example 1: Barn Owls select their prey based on a number of factors: energy content of the prey (adult vs baby rat), energy needed to pursue the prey (more for adult rat than baby ray), and energy required to consume prey (turtle [shell] vs rat [no shell]). A Barn Owl may choose to pass over a turtle in favor of a baby rat because the net energy gain of going after the turtle would not be favorable.
Describe ALTRUISTIC BEHAVIOR in terms of fitness and give an example.
Altruistic behavior -(self sacrifice) that has a fitness loss (potential cost) to the individual exhibiting the behavior and a fitness benefit (gain) to the recipient of the behavior, resulting in an increase in the altruistic individuals inclusive fitness.
Example: Prairie dogs use altruistic (alarm calling) behavior to alarm relatives when a predator is present. The sentries (the look out) watch for predator (snakes and hawks) and alarms others of what is coming.
Explain why, in the prairie dog example, their “truth-telling” and their “lying” both increase the fitness of the alarm giver. . . Include direct fitness, indirect fitness, and competition in your answer.
Prairie dogs have sentries or alarm caller that watches for predators while other prairie dogs eat. Sentries call out warning their offsprings (DIRECT FITNESS) and relatives (INDIRECT FITNESS) that a predator is near the burrow. The calls differ depending on the predator that is near (snake or hawk). Sometimes these sentries make deceitful calls to unrelated prairie dogs deceiving them to run towards the predator. This eliminates COMPETITION, and increases total fitness.
Describe each of the three basic types of population distribution (random, uniform, and clumped; know which are common and which are uncommon; say why the common one is so common.
Random = is uncommon because there is no relationship between location of individuals. Uniform = is uncommon because individuals location is predictable. Clumped = is common because certain places have individuals and others don't.
