(BIO120H1)
Topic: Community Ecology, Mostly Competition
Community Ecology, Mostly Competition
• Introduction to community ecology, especially species interactions
• Intra — versus inter — specific competition
• Lot — Volterra model of competition: extension of logistic growth
model
• Problem of species coexistence, paradox of the plankton
• Testing for competition empirically
• Community structure: species richness and composition, alpha, beta,
and gamma diversity
Other Statistics You Can Calculate from Life Tables
• Life expectancy, ex: expected years of life left to an individual of age x
➢ Important for selling life insurance!
• Reproductive value, la: expected number of future daughters left to an
individual of age x
➢ Important for how selection acts on behavior!
Reproductive Value in Humans
, What Might vx Affect?
• Success of captive breeding/release programs for conservation: should
release animals with highest reproductive value
• Prospective success following dispersal to new habitats: roaming behavior
should coincide with age of high vx
• Age of high vx should maximize attractiveness to potential mates
Why Do We Age? ("Senesce")
• Antagonistic pleiotropy theory of Gr Williams
• Pleiotropy 4 one gene may have multiple different functions
• "Antagonistic pleiotropy" 4 a gene may have opposite effects on survival at
different ages
• A gene with positive value in young animals but negative value in old
animals will be favoured by natural selection.
• Reproducing early increases fitness
• Accumulation of such genes causes senescence
• E.g. p53 suppresses tumours in youth, but later destroys stem cells
What Determines Where Species Live?
• Dispersal
• Abiotic Conditions
➢ Climate
➢ Nutrients
• Species interactions
➢ Competition
➢ Predation
➢ Mutualism
• Species in a community
Species Interactions
• Interactions between species are often classified by their outcome (± or -)
• An over — simplification, but a useful starting point
• Competition hurts both species
• Predation benefits predators, but hurts prey (host — parasite and plant —
herbivore interactions also +/- )
Topic: Community Ecology, Mostly Competition
Community Ecology, Mostly Competition
• Introduction to community ecology, especially species interactions
• Intra — versus inter — specific competition
• Lot — Volterra model of competition: extension of logistic growth
model
• Problem of species coexistence, paradox of the plankton
• Testing for competition empirically
• Community structure: species richness and composition, alpha, beta,
and gamma diversity
Other Statistics You Can Calculate from Life Tables
• Life expectancy, ex: expected years of life left to an individual of age x
➢ Important for selling life insurance!
• Reproductive value, la: expected number of future daughters left to an
individual of age x
➢ Important for how selection acts on behavior!
Reproductive Value in Humans
, What Might vx Affect?
• Success of captive breeding/release programs for conservation: should
release animals with highest reproductive value
• Prospective success following dispersal to new habitats: roaming behavior
should coincide with age of high vx
• Age of high vx should maximize attractiveness to potential mates
Why Do We Age? ("Senesce")
• Antagonistic pleiotropy theory of Gr Williams
• Pleiotropy 4 one gene may have multiple different functions
• "Antagonistic pleiotropy" 4 a gene may have opposite effects on survival at
different ages
• A gene with positive value in young animals but negative value in old
animals will be favoured by natural selection.
• Reproducing early increases fitness
• Accumulation of such genes causes senescence
• E.g. p53 suppresses tumours in youth, but later destroys stem cells
What Determines Where Species Live?
• Dispersal
• Abiotic Conditions
➢ Climate
➢ Nutrients
• Species interactions
➢ Competition
➢ Predation
➢ Mutualism
• Species in a community
Species Interactions
• Interactions between species are often classified by their outcome (± or -)
• An over — simplification, but a useful starting point
• Competition hurts both species
• Predation benefits predators, but hurts prey (host — parasite and plant —
herbivore interactions also +/- )
