BIS2B FINAL

• beneficial interactions (+): individual has more offspring or survives longer increases population growth
• harmful interactions (-): individual has fewer offspring or dies sooner decreases population growth
• competition:

  • negative, negative effect
  • both individuals are harmed by the interaction
• ammensalism:

  • negative, zero effects
  • one individual is harmed, the other unaffected
• predator/prey interactions:

  • positive, negative effect
  • one individual benefits and the other is harmed
• mutualism:

  • positive, positive effect
  • both individuals benefit from the interaction
• commensalism:

  • positive, no effect
  • one individual benefits, other is unaffected by the interactions
• interspecific interaction play a role in population regulation, maintain or disrupt species diversity, and act as agents of natural selection
• beneficial interactions increase a species' carrying capacity
• harmful interactions reduce a species' carrying capacity or cause extinction
• interspecific interactions can select for tightly coevolved traits and anti-predator or parasitism adaptations
• competition occurs when individuals harm one another
• competition leads to decreased growth, survival, or reproduction; lower population growth rates
• intraspecific competition: competition between members of the same species
• interspecific competition: competition between members of two or more different species
• intraspecific competition reduces survival through self-thinning
• self-thinning in plants is when many small seedlings of the same species compete with each other leading to very few but large trees in the future
• self thinning:

  • as population gets smaller, mass of the organism gets bigger
• self-thinning is plotted on a semi-log graph
• interspecific competition leads to species inhibiting the growth of the other species regardless of differing in competitive abilities
• competitive exclusion principle: two species that use the same resources in the same way CANNOT coexist; one will drive the other extinct
• R* rule: the species that can suppress the resource to the lower equilibrium level will competitively exclude the other species
• the species that can push the resource to the lower value (concentration or availability) will be the winner of the competition
• species can only coexist when they differ in the way they use resources or have spatial segregation
• niche utilization curve: performance of a species for a range of environmental conditions (food size, temperature)
• coexistence is determine by the size of niche overlap
• when there is little niche overlap, niche partitioning allows coexistance
• when there is large niche overlap, competitive exclusion is likely
• when an organisms has a broad variation of a certain trait, it indicates that the species is taking all of the resources on the island
• negative frequency dependence: when one species is more common, it faces greater competition for special resources
• in negative frequency dependence, being rare can be advantageous because you require different resources, less competition
• negative frequency dependence promotes coexistence
• positive frequency dependence: decreases variation because the more common types excludes the other
• character displacement: differences between similar species are greater in places where they co-occur and minimal in places where their distribution do not overlap
• microevolution: changes in allele frequencies across generations

  • small-scale changes
  • short time frames
• macroevolution (speciation): accumulated microevolutionary changes that a new group arises

  • large-scale changes
  • long time frames
• biological species concept: a species is a group of interbreeding natural populations that are reproductively isolated from other groups
• the pros of the biological species concept is that it is easy to understand based on mating possibility
• the con of the biological species concept is that it doesn't apply to asexual organisms and we don't always have mating data
• phylogenetic species concept: a species is a group of organisms that share a common ancestor and are genetically similar