Evolution | CH 15

Coevolution

The process where species exert selective pressures on each other, affecting each other's evolution.

Mutualism

A positive/positive relationship between species that raises each other's fitness.

Commensalism

A positive/neutral relationship where one species benefits without affecting the other's fitness.

Parasitism

A negative/positive relationship where one species benefits at the expense of the other's fitness.

Reciprocal selection

Selection occurring in two species due to their interactions, a critical aspect of coevolution.

Geographic Variation in Coevolved Traits

Based on population genetics, coevolved traits are expected to display geographic variation in their evolution.

Pleiotropy

Some variation in coevolved traits may result from pleiotropy, where enhanced resistance can come at the expense of other traits like competitive ability.

Geographic Mosaic Theory of Coevolution

The theory proposes that coevolutionary interactions vary geographically, leading to different outcomes in different populations, forming a mosaic of coevolutionary traits.

Antagonistic Coevolution

In antagonistic relationships, such as between parasites and hosts, negative frequency-dependent selection can drive reciprocal coevolution, favoring genetic variation for host resistance and pathogen virulence.

Coevolutionary Alternation

Occurs when one species interacts with multiple other species, shifting its interactions over generations to maintain a dynamic coevolutionary process.

Selection Experiment

Researchers conducted a selection experiment to produce highly resistant flies, showing that strong resistance incurs costs and affects competitive ability.

Cuckoo Deception

Cuckoos lay their eggs in the nests of other bird species, deceiving the host birds into incubating and rearing the cuckoo chicks.

Coevolutionary Arms Race

A process where species invest in defenses and counter-defenses against each other, leading to an escalation similar to the increase in nuclear weapons during the Cold War.

Reciprocal Coevolution

Species interact antagonistically, exerting reciprocal directional selection on each other, resulting in the evolution of new weaponry in response to the other's defenses.

Geographic Mosaic Theory

The pattern of coevolutionary escalation and its costs, where populations of predators and prey are sometimes well-matched in their traits, leading to a geographic mosaic of coevolution.

Virulence

The degree of harm caused by a parasite to its host during coevolution, with different parasites evolving varying levels of harm, such as the swift, severe effects of the Ebola virus compared to milder infections like the common cold.

Trade-off Hypothesis

Scientists' explanation of how parasites can evolve different levels of virulence, representing a trade-off between selection within hosts for rapid replication and selection for transmission between hosts.

Attenuated Coevolution

The gradual weakening of reciprocal selection between host and pathogen due to the evolution of lower virulence, leading to slower coevolution.

Mutualists

Organisms engaged in mutualistic interactions where alleles favored by selection benefit another species, resulting in positive frequency-dependent selection and rapid coevolution.

Long-Tongued Flies

Flies in South Africa with long tongues that coevolve with flowers they pollinate, leading to a geographic mosaic pattern of coevolution.

Mutualisms Encompassing Many Species

Mutualistic interactions involving multiple species, such as fruit-eating birds dispersing seeds for various plant species, leading to complex mutualistic networks that can coevolve.

Müllerian mimicry

When several harmful or distasteful species resemble each other in appearance to facilitate the learned avoidance of predators.

Batesian mimicry

A type of mimicry where a harmless species resembles a harmful or distasteful species (model species) to derive protection from predators.

Coevolution

The process where two or more species reciprocally affect each other's evolution, often leading to adaptations in response to each other.

Convergent evolution

The independent evolution of similar features in unrelated species due to similar environmental pressures.

Arms race

Escalated and rapid coevolution of weapons and defenses between species due to antagonistic interactions.

Introgression

The movement of genetic material across species boundaries, facilitating rapid convergence onto shared traits.

Speciation

The process by which new species evolve from existing ones over time through various mechanisms, including coevolution.

Frequency-dependent selection

Selection where the fitness of a genotype depends on its frequency in the population, leading to the maintenance of genetic variation.

Mutualism

A type of symbiotic relationship where both species involved benefit from the interaction.

Cheaters

Individuals that exploit mutualistic interactions for their own benefit, potentially leading to the collapse of the mutualism or the evolution of defenses.

Pinecone Scales

Protective structures on pinecones that red squirrels can pull away to access the seeds underneath.

Trade-off

The situation where pine trees must balance their defenses against red squirrels and crossbills.

Diversifying Coevolution

A process leading to significant differences between populations due to coevolution.

Geographic Mosaic

A pattern of coevolution where interactions between species vary depending on the local environment.

Reproductive Barrier

A mechanism that prevents gene flow between populations, potentially leading to speciation.

Antagonistic Coevolution

Coevolutionary interactions that involve conflicts between species.

Mutualism

A type of relationship where both species benefit from the interaction.

Endosymbiosis

A form of mutualism where one species lives inside another, benefiting both partners.

Aster Yellows

A plant disease caused by bacteria injected by aster leafhoppers while feeding on plant sap.

Mutualists

Organisms that engage in mutualistic relationships with coevolutionary partners.

Endosymbiont

A mutualistic organism that lives within the body or cells of another organism.

Cospeciation

Occurs when a population speciates in response to, and in concert with, another species.

Mitochondria

Membrane-bound structures in eukaryotic cells that produce energy using oxygen, sugar, and other molecules; evolved from free-living bacteria.

Plastids

Photosynthetic organelles in plant cells that originated from endosymbiotic bacteria.

Retrovirus

An RNA virus that uses reverse transcriptase to integrate its genetic material into the host cell's DNA; examples include HIV.

Endogenous retroviruses

Viruslike stretches of DNA that descend from retroviruses infecting sperm or egg cells, becoming part of the host's genome over generations.

Horizontal transmission

The pathway where viruses spread from host to host, leading to the modern virus.

Jumping genes

Mobile genetic elements that can move through the genome, potentially originating from retroviruses, and can disrupt normal cell functions.

Coevolution

The process where endogenous retroviruses and mobile genetic elements have evolved alongside host genomes, impacting each other's fitness.

Domesticated parasites

Mobile genetic elements that have taken on new functions benefiting the host, blurring the line between parasites and beneficial elements.