History and meaning of the word “Ecology” Definition Oikos, ology - the study of the house - the place we live Etymology – study of the origin and development of a word Earliest - Haeckel (1869) - comprehensive science of relationship of organism and environment Elton (1927) - scientific natural history Andrewartha (1961) - Scientific study of the distribution and abundance of organisms Krebs (1985) - scientific study of the interactions that determine the distribution and abundance of organisms Note that all talk about “scientific” Why??? Separation of induction (natural history) and deduction (scientific method)

Definitions (levels of ecological organization) Individual (can be difficult to define! Generally, a biological organism that…) Lives, reproduces, dies Has a unique genotype Is the unit of selection Is autonomous of other organisms Population (a collection of individuals in an area, of the same species, that…) Interact with one another Interbreed Species (characterized by…) Individuals, naturally capable of interbreeding and producing fertile offspring Community A group of populations (species) in a given place - usually implies that populations (species) interact Ecosystem A biotic community and its abiotic (physical) environment

Basic Population Biology Basic Population Biology - losses may matter Basic Population Biology 100 20 40 60 80 Population Time K

Basic Population Biology- Unlimited Growth = Malthusian Growth or exponential growth Logic: Population at time t = Nt Population at time t + 1= Nt+birthrate (b) + immigration (i) + emigration (e)+ death rate (d) Where t= time t and t+1= sometime after that

Exponential Growth r = b-d Assumptions: Basic Population Biology - losses may matter Exponential Growth Assumptions: 1) Emigration = immigration, then Nt+1 = Nt+births (b) - deaths (d) where b and d are instantaneous estimates 2) Generations overlap 3) Resources are unlimited Now let the instantaneous per capita rate of growth (r) equal the birth – death rate: r = b-d

Exponential Growth - calculation Basic Population Biology - losses may matter Exponential Growth - calculation Births > Deaths r > 0 Nt = N0ert N0 = population at time 0 r= per capita rate of growth (b – d) t= time e= base of the natural log (~2.72) 100 80 60 40 Population Essentially same formula as compounded interest 20 20 20 40 40 60 60 80 80 100 100 Time

Exponential Growth - calculation Basic Population Biology - losses may matter Exponential Growth - calculation Births < Deaths r < 0 Nt = N0ert N0 = population at time 0 r= per capita rate of growth (b – d) t= time e= base of the natural log (~2.72) 100 80 60 40 Population 20 20 20 40 40 60 60 80 80 100 100 Time

Exponential Growth – an Understanding of Rates Basic Population Biology - losses may matter Exponential Growth – an Understanding of Rates Let r = 0.20 0.10 0.05 N t Rate of growth of population = 100 N t High population size (N), population growth rate is high because rN = large value Low population size (N), population growth rate is low because rN = small value 80 Using calculus we can derive a function for the instantaneous rate of growth of populations. The rate of change of the population is equal to growth rate x the population dn / dt = rN 60 Population 40 20 20 20 40 40 60 60 80 80 100 100 Time

Exponential Growth - why is growth unlimited? Basic Population Biology - losses may matter Exponential Growth - why is growth unlimited? The assumption is that the per capita growth rate (r) is unrelated to population size (N). This means: 1) Birth rates are unaffected by population size, and 2) Death rates are unaffected by population size Does this make sense? Birth rate (b) remember r = b - d Per capita growth rate (r) Death rate (d) Population (N) Population (N)

Per capita growth rate (r) Basic Population Biology - losses may matter Limited Growth Assumptions: 1) Resources become limited as populations increase Thus, per capita rate of growth must decrease with increasing population Per capita growth rate (r) Resources Population (N) Population (N)

Per capita growth rate (r) Basic Population Biology - losses may matter Limited Growth – caused by changes to birth and death rates that are density dependent Per capita growth rate (r) Birth rate Death rate Population (N) Rate Population (N)

Limited Growth – density dependence Basic Population Biology - losses may matter Limited Growth – density dependence Exponential rate of population growth 20 40 60 80 Population 100 Time K= carrying capacity K dn / dt = rN Logistic (limited) rate of population growth dn / dt = rN (K-N) K 100

Key consequence of density dependence: Population regulation: when population fluctuations are bounded so as not to increase indefinitely or decrease to extinction 20 40 60 80 Population 100 Time ? ? 100

Logistic (limited) growth – implications for conservation I Basic Population Biology - losses may matter Logistic (limited) growth – implications for conservation I Excess Adults K / 2 Adult Population Population Growth Rate 100 20 40 60 80 Population Time K Excess Maximum K

Logistic (limited) growth – implications for conservation II Basic Population Biology - losses may matter Logistic (limited) growth – implications for conservation II Excess Juveniles - Compensation 20 40 60 80 Population 100 Time Excess K Adult Population 100 Juveniles

Excess or Resource – should the buffers be given away? Basic Population Biology - losses may matter Excess or Resource – should the buffers be given away? K K / 2 Maximum Excess Excess Population Growth Rate Adult Population K Adult Population Juveniles

Excess or Resource – should the buffers be given away? Basic Population Biology - losses may matter Excess or Resource – should the buffers be given away? Provides buffer for cumulative effects Provides buffer for natural and anthropogenic impacts K Adult Population Population Growth Rate K / 2 Maximum Buffer Buffer Adult Population K Juveniles

Basic questions are: 1) Do density-dependent processes produce excess individuals (that are essentially wasted) or population buffers that provide a safety mechanism against I) Natural variability II) Natural disturbances III) Additional anthropogenic impacts 2) Are population (demographic) buffers the property of the general public or industry? 3) Example: fish losses due to fishing (adults) and power plant entrainment (larvae)

Population Structure: Contrary to assumptions of Logistic Growth, not all individuals in a population are the same! Structure: relative abundance of individual traits among individuals in a population: i) size ii) age iii) stage (e.g., larvae, juveniles, adults) iv) sex v) genetic (distribution of genotypes throughout population) vi) spatial (distribution and interaction of individuals within and among populations) All of these influence per-capita rate of mortality (D) and reproduction (B)

Size Matters: Bigger Fish Produce Far More Larvae Approx. 7-fold increase Approx. 11-fold increase

Fished population Non-fished population

black rockfish (Sebastes melanops). Age matters: older females produce higher quality larvae with a higher likelihood to survive Larval growth in length (mm/day) Time (d) to 50% larval mortality Berkeley et al. 2004. Fisheries 29: 23-32. Berkeley et al. 2004. Ecology 85:1258-1264. Maternal age (yr) Moreover: Different aged fish spawn at different times Bobko, S. J. and S. A. Berkeley. 2004. Fishery Bulletin 102:418-429.

Key consequence of density dependence: Population regulation: when population fluctuations are bounded so as not to increase indefinitely or decrease to extinction 20 40 60 80 Population 100 Time ? ? 100

“Bipartite” life cycle of benthic marine organisms with pelagic larvae survive, grow, develop, disperse Pelagic Environment reproduce settlement Benthic Environment One key life history trait characteristic of many marine fishes is what fish heads refer to as a “bipartite” life cycle, in which Different life stages are adapted for life in either the benthic and pelagic environment. BUT “CLOSED” cycle is misleading… Adult Juvenile survive, grow, mature

“Bipartite” life cycle of benthic marine fishes with pelagic larvae For those species Young produced by adults in a local population

“Closed” Populations “Open” Populations Production Supply Production Supply Little or no exchange among populations Significant exchange among populations Production Supply Supply Production

Spatial structure of populations implications for gene flow, genetic diversity and population persistence “Closed” populations: self-replenishing Limited dispersal: stepping-stone Single source: mainland - island Multiple sources: larval pool LARVAL POOL

Spatial structure creates “metapopulations” Collection of isolated self-replenishing sub-populations Collection of highly connected sub-populations Mostly self-replenishing Separate dynamics No “rescue effect” from other sub-populations Persistence based only on local sub-population size and processes, density-dependence, independent of other sub-populations Little self-replenishment Sub-populations with very similar dynamics Highly influenced by “rescue effect” from other sub-populations Persistence based largely by system-wide dynamics and processes, especially the number of connected sub-populations

Spatial structure creates “metapopulations” Metapopulation: collection of partially-connected sub-populations Some self-replenishment, some external replenishment Variation in sub-population dynamics (asynchronous) Influenced by “rescue effect” from other populations Persistence based on both local and system-wide dynamics and processes, especially the size and number of sub-populations, and density-dependence

Population Attributes Life History Traits (individual, heritable, species-wide) reproductive modes longevity, fecundity life cycle Population Attributes distribution structure (size, age, genetic, spatial) dynamics One of the most fascinating aspects of ecology, and a central focus of evolutionary ecology, is understanding the ecological consequences of life history traits. These are heritable traits characteristic of a species, such as longevity… , that can influence the distribution, structure and dynamics of populations… Community Attributes biogeography structure (composition, abundance) dynamics diversity