Life History #7: Life History Strategies, Trade-Offs

Life History: Consists of major events related to organisms’ development, growth, reproduction, and survival

Life History Strategy: Pattern in timing and nature of history events averaged across all individuals in species Example: - When to metamorphose (direct development)? - How fast to grow? - How large to grow? - When to begin reproducing? - How many offspring, and of what size? - Whether to care for offspring? - How often to breed? - How long to live? Note: Mode of Reproduction (sexual/asexual) = Basic Life History trait - Sexual reproduction very costly, but can “keep ahead” to avoid pathogens rather than being killed off due to being genetic identical

Offspring Number vs Offspring Survival: - Clutches w/ fewer eggs = all/most young birds survive fledging - Clutches w/ more eggs = fledging survival chance were poorer

Offspring Number vs Offspring Size: - Plant species producing lot seeds tend to produce small seeds - Plant species producing few seeds tend to produce large seeds

Offspring Number vs Parental Survival/Growth - Producing more cones = slower tree growth = less growth rings

Indirect Development: - Take advantage of resources in other habitats - Avoid immediately competing with adults of own species - Good for dispersal Complex Life Cycles: 2 distinct life stages

Direct development: - Avoid predators in other habitats - Already in place that your species can survive in - Avoid “washing away”