BIOL 4015 EXAM 2: Habitat Fragmentation

heterogeneous

patches of less suitable habitat in the mosaic require adaptations to maximize fitness

habitat fragmentation

rapid alteration of landscape spatial structure including deleterious genetic, population, and species effects on resident species

research as focused on _________ ______________ rather than ________________ _____________ that minimize biodiversity loss

patch dynamics (conservation approach), land-use methods (sustainable production approach)

important to consider ___________ of habitat remaining and ______________ _______________________ of habitat patches

amount, spatial configuration

habitat loss is a direct result of

fragmentation

island biogeography theory

explains how species come to be distributed among oceanic islands

fragmentation usually results in declining ___________ ___________ through time

patch area:

- results in many small patches

population level

limited resource availability, reduced colonization rates, altered reproductive success

limited potential population size from:

1. environmental stochasticity (all individuals)

2. demographic stochasticity (some individuals, small N)

3. natural catastrophes

4. reduced genetic diversity (genetic drift)

5. altered resource availability and the interaction with 1-4

community level

changes in patch species composition

- dependent on species requirements and dispersal abilities

- evolution of metapopulation and metacommunity ecology

- reduction of richness in small patches

fragmentation increases edge effects

smaller patches --> relatively greater edge habitat

- patch size reductions increasingly expose interior forces

- edges hotter, drier, windier, higher wavelength intensities, composition --> altered animal composition

- edge effects inclde edge extent and magnitude

fragmentation results in various patch shape complexities

edge:area ratio useful metric, minimized with perfect circle

greater shape complexity

1. increase colonization rates

2. increase environmental heterogeneity

3. reduce core area for interior patch specialist

4. research indicates:

a) shape complexity increases exponentially with increasing patch size

fragmentation results in increased patch isolation

- changing characteristic in time and space, depends on:

1. time since isolation

2. distance between patches

3. temporal changes in matrix characteristics

4. dispersal traits of species

species relaxation

initial richness declines through time as species cannot maintain viable populations

habitat corridors

1. allow movement between isolated populations

2. potential for both positive (dispersal, genetic connectivity) and negative (spread of diseases, invasive species) impacts

fragmentation effects related to matrix quality

1. depends on organisms involved

2. higher (organic farm, high shade) and lower quality (traditional farm, low shade) matrix environments

fragmentation effects in natural systems factors:

1. interactions between drivers of fragmentation

2. poor understanding of species life histories

3. temporal changes in fragmentation effects

4. synergistic interactions between fragmentation and other processes

habitat degradation can be viewed as alteration of the ________________ and _________________ environments

biophysical alteration: invasive species, species irruptions, altered hydrology

chemical alteration: nutrient increases/decreases, herbicides/pesticides, industrial pollutants, acid deposition

marine habitats biophysical and chemical impacts

biophysical: climate change, altered currents, upwellings, sea level rise, reef loss

chemical: nutrients --> dead zones, acidification --> massive biodiversity loss