Salit Kark The Biodiversity Research Group Department of Evolution, Systematics and Ecology The Silberman Institute of Life Sciences The Hebrew University of Jerusalem Conservation Biology (Ecology) Lecture 6 November 2009 Dr. Salit Kark. The Hebrew University of Jerusalem

Conservation of populations: We will discuss:  Demographic Processes  Metapopulation structure  Population Viability Analysis (Credit to Kedong Yin for following slides)

Lande: Demography may usually be of [equal or even] more immediate importance than population genetics in determining the minimum viable sizes of wild populations Demographic processes

Mechanisms of Population Regulation: A Hierarchy Approach Landscape Level Population Level Individual Level Land use change Climate change Succession Disturbance Birth rates Death rates Immigration Emigration Sex ratio Age structure Growth rates Feeding rates Habitat selection Predator avoidance

Dr. Salit Kark. The Hebrew University of Jerusalem

Hawaiian Monk Seal Population Dr. Salit Kark. The Hebrew University of Jerusalem

Hawaiian Monk Seal Population 1 acre = ~4 dunams Dr. Salit Kark. The Hebrew University of Jerusalem

Hawaiian Monk Seal Population As Skate & Whale were washing away, a new problem arose. A group of Galapagos sharks developed a new pattern. They started aggressively patrolling the shallow water around Trig Island for seal pups… Today ~1000 exist of the seal… Dr. Salit Kark. The Hebrew University of Jerusalem

Coastal Guard in Green island Coastal Guard out of Tern island Green Island Tern Island Number of Seals Hawaiian Monk Seal Population changes on two islands occupied by US Coastal Guard Juvenile survival is important in conserving seal populations 1976 endangered Dr. Salit Kark. The Hebrew University of Jerusalem

One of the demographic factors of fundamental importance for the survival of small populations: population regulation

Density-independent Rate of Birth or Death Density-dependent Population Density Population regulation: density-regulation Dr. Salit Kark. The Hebrew University of Jerusalem

Habitat-specific demography Island theory Metapopulation theory Dr. Salit Kark. The Hebrew University of Jerusalem

Equilibrium Theory of Island Biogeography: Species richness is the balance between colonization and extinction rates LowHigh FS NS FLNL ColonizationExtinction Far: F Large: L Near: NSmall: S Species Richness # Rate of Colonization Rate of Extinction Dr. Salit Kark. The Hebrew University of Jerusalem

The key conservation legacies of the dynamic theory of island biogeography were: 1) Arriving at a few robust empirical generalizations of biology and ecology Number of species in island reaches an equilibrium (at a relatively fixed no) over time There is constant turnover in an island: new species arrive while others disappear number of species declines with increasing distance from mainland Immigration and recolonization rates decline with increasing isolation Extinction rates decline with island size 2) Species-area relationship 3) The metaphor of a refuge, patch as an island Dr. Salit Kark. The Hebrew University of Jerusalem

Shift to Metapopulation paradigm in conservation: Shift in the conception of nature as an equilibrium world to non-equilibrium one Metapopulation concept incorporates spatial structure into population dynamics – most significant, linked to habitat fragmentation Metapopulation models “rescued” small sites from their devaluation by island biogeography theory. Dr. Salit Kark. The Hebrew University of Jerusalem

Paradigm Shift (Hanski and Simberloff 1997) Dr. Salit Kark. The Hebrew University of Jerusalem

Metapopulation: A population of a species that consists of several subpopulations linked together by immigration and emigration. Dr. Salit Kark. The Hebrew University of Jerusalem

A comparison between island biogeography and metapopulation Equilibrium: Species richness vs. population Community vs. population approach: Island theory ignores the changes in the presence and absences of individual species Among-patch movement Dr. Salit Kark. The Hebrew University of Jerusalem

Metapopulation, linked by local subpopulations 1.Patchiness 2.Size 3.Spatial structure 4.Linkage Dr. Salit Kark. The Hebrew University of Jerusalem

Formal Definitions (Hanski and Simberloff 1997) Local Population : “Population, subpopulation, deme” Set of individuals that live in the same habitat patch and therefore interact with each other Metapopulation: Set of local populations within some larger area, where typically migration from one local population to at least some other patches is possible

Metapopulation Sources and Sinks Sources: good habitats where local reproductive success is greater than local mortality and individuals disperse outside their natural patch to find a place to settle and breed. Positive r: B+I>D+E As little as 10% of a metapopulation in source habitats may be responsible for maintaining the 90% of the population found in the sinks Dr. Salit Kark. The Hebrew University of Jerusalem

Metapopulation Sources and Sinks Sinks: poor habitats where local reproductive success is less than local mortality and the subpopulations rely on immigrations to avoid extinction Negative r: B+I<D+E Dr. Salit Kark. The Hebrew University of Jerusalem

Sources and sinks in a metapopulation Source Sink Source Dr. Salit Kark. The Hebrew University of Jerusalem

Note: Fragmented populations that are usually not linked are not considered to be a metapopulation. Rescue Effect: local extinction of a subpopulation can be prevented by occasional immigrants that arrive from neighboring patches Dr. Salit Kark. The Hebrew University of Jerusalem

Classical metapopulation A set of small patches that are individually prone to extinction but large enough and close enough to other patches that recolonization balances extinction. Dr. Salit Kark. The Hebrew University of Jerusalem

Mainland-island metapopulation A mixture of large and small patches close enough to allow frequent dispersal from an extinction-resistant mainland to the extinction-prone islands Dr. Salit Kark. The Hebrew University of Jerusalem

Patchy metapopulation Patches so close together that migration among them is frequent; hence the patches function over the long run as a continuous demographic unit Dr. Salit Kark. The Hebrew University of Jerusalem

Nonequilibrium metapopulation A set of small patches in which each has a high probability of extinction and among which little or no migration occurs. Local extinction rates are not offset by recolonization, resulting in overall decline toward regional extinction. Separate metapopulations based on very low likelihood of dispersal among them Functional subpopulation based on frequency of dispersal beyond them Dr. Salit Kark. The Hebrew University of Jerusalem

A. PatchyB. Classical C. NonequilibriumD. Mainland-Island A dispersal buffer: an isoline of dispersal probability A subpopulation Metapopulation Types Separate metapopulations Dr. Salit Kark. The Hebrew University of Jerusalem

Patchy Classical Mainland- Island Mainland- Mainland NonequilibriumDisjunct Highly connected Patch isolation Highly isolated All smallAll large Patch Size Dr. Salit Kark. The Hebrew University of Jerusalem