Ecology PDF

Life histories Life histories are the attributes of the life cycle through which an individual passes, with particular reference to survival and reproduction Expressed through behaviour, physiology, anatomy Genetic variation and phenotypic plasticity...

Life histories Life histories are the attributes of the life cycle through which an individual passes, with particular reference to survival and reproduction Expressed through behaviour, physiology, anatomy Genetic variation and phenotypic plasticity 9  Life history traits Important life history traits include: Age at maturity Size at maturity Fecundity (number of offspring) Size of offspring Frequency of reproduction Canada’s largest woodpecker: the Pileated Woodpecker 10  Age at maturity Age at maturity varies across different timescales: Minutes (e.g. many bacteria) Meadow voles mature in Months (e.g. small less than 2 months mammals) need to be to large Decades (e.g. many grow young sharks, whales) Porbeagles mature in 7 (male) or 13 (female) years11 - - FIGURE 8.3 variations' themes 12  Size at maturity Size at maturity increasing relationship linear between and age at size of animal at maturity maturity are and the at age correlated: the animals maturity Large-bodied animals have later age at maturity Bony fish Sharks & rays Mammals FIGURE 8.8 13  Fecundity Annual fecundity is the number of offspring produced by an individual during a breeding season Annual fecundity is influenced both by the number of reproductive events and the number - of offspring per event - - FIGURE 8.4 14  Fecundity The number of reproductive events varies from once in a lifetime to repeatedly over centuries Jewelweed reproduces once then dies (semelparous) - influence life history - your investing differently - > - grow eggs , produce sperm VS growing body FINITE RESOURCES Red pines reproduce for = centuries (iteroparous) - 15  Fecundity In some cases, fecundity shows little variation with age Black-capped chickadee produces equal # of males and females no age related variation 16  waituntilyour oder and differentiallyinvesa Fecundity In other cases, fecundity varies dramatically with age I mill eggs Within some species, = fecundity increases - with female body size - Atlantic cod & I.S 7 17 mil  Size and number of offspring Across species, there is a negative correlation between size and number of offspring: Organisms produce Pacific halibut produce up numerous small to 1 million eggs per year offspring, or few large offspring Humpback whales produce FIGURE 8.7 one calf every 2-3 years 18  Parental care Many organisms invest heavily in parental care For example, female grey seals may lose up to 40% of their mass during lactation Other organisms leave Grey seal offspring survival at the mercy of the environment Example: Atlantic Cod release eggs straight into the ocean Atlantic cod 19  Reproductive effort Proportion of total energy devoted to reproduction, including: – Physiological effort (e.g. energy demands) – Anatomical effort (e.g. gonad development) – Behavioural effort (e.g. migration) FIGURE 8.1 High reproductive effort (bulging eggs) by brook trout 20  Life history trait variability face invest a lot Higher chance survival- predators a reproduce invest in sematic Life history growth Brook Trout at Brook Trout at traits vary: Freshwater River Cripple Cove Creek Among species Among populations Within fish populations smaller devole to egg production FIGURE 8.6 make Sura plentiful 21  Reside Dace endangered - Obligate nest parasite - - aerial insectivore - resides in Toronto - urbanization stressors Urban Stressors i) road salt ii) artificial light -> Street lights , Circadian rhythm iii) turbidity I dirt can't see iv) thermal stress Thermal Stress took fish ? a put into water bath I how not temp can handle turn CT up temp until they pass out > - - max policy directives for Toronto Captive Breeding and Reintroduction leave with other fish eggs study ecological parameters/ evolutionary FREC Captive breeding -  Adaptation Life history traits show adaptation Example: tiny dust-like seeds of orchids spread with the wind Orchid flowers produce millions of tiny seeds Example: large coconuts are suited for long- Coconuts produce few distance transport over large seeds the ocean 22  Ex. body mass and maturity Constraints at age are with co-varying eachother big animal is a how quickly a pop can grow Life history traits constrain each other: Bony fish Sharks & rays Mammals Bony fish Bony fish Sharks & rays Sharks & rays Mammals Mammals Age at maturity increases Population growth with adult body size decreases with body size mouse - small size body rapid population growth = rate FIGURE 8.8, 8.10 whale to larger body size = Slower max population growth rate 23  Ex - multiple Bet-hedging strategies. reproductive attemps over time OR in lay eggs many as organisms evolve follow the best way to devote resources (body growth , reproductive growth) Streams organisms bet-hedging strategies life history traits Environments vary spatially and temporally -> that avoid an organism of its putting in all eggs one basket Harsh conditions env is unpredictable disadvantage species giant ↓ with “all eggs in one destroy storm basket” if in Stream laid eggs only that Unpredictable stream TROUBLE Rep success O environments favour species which exhibit diverse strategies to spread the risk (a.k.a. Indian Tobacco shows bet hedging) dramatic plasticity in timing of germination FIGURE 8.14 24  spread across rish opportunities Bet-hedging - To “hedge your bets” is to do things that will prevent greater loss if events don’t go as you hope green Ex. bet on both red and > - you assure some chance of In ecology, bet-hedging a win occurs when an animal has lower fitness in optimal conditions, but increased fitness in suboptimal condutions reduce the variance in fitness over many generations even if it involves a sacrifice for 25 a particular generation 3x I only streamisgoingtobe productiveenon to Waste some. one  Bet-hedging strategies Large female cod have longer spawning periods, are more likely to spawn in a favourable period bigger fish use its larger 7 mill eggs body size to hedge its bets and produce eggs over an extended period overlap nutrient availability ↳ spawn allow offspring over larger to survive period e overlap w period of nutrient availability did all spawning didn't either overlap of nutrients periods & O rep contribution I mill eggs FIGURE 8.16 26  Bet-hedging strategies By laying eggs over longer intervals, this fish hedges her bets FIGURE 8.16 27