Population Ecology Distribution Abundance K Harms photos from

Population Ecology: Distribution & Abundance K. Harms photos from north of Manaus, Brazil

Population A group of individuals of a species that occupy a given place at a given time Photo of members of a tadpole population from http: //www. whateats. com/what-eats-a-tadpole-2

Distribution Local distribution – generally patchy, not continuous (which reflects patchy character of habitat, dispersal history, etc. ) Geographic distribution – the entire geographic range Canyon wren (red) Cerulean warbler (blue) “X’s denote [Breeding Bird Surveys] on which the focal species were never detected over this period [1993 -2002], while filled circles indicate where the focal species were detected. ” Hurlbert & White (2005) Ecology Letters, Fig. 1

Abundance Population size – the number of indivs. in the pop. Population density – no. indivs. per unit area Photo from http: //vitalsignsme. org/observation/species-comptonia-peregrina-was-found-flaming-toast-2010 -10 -06

Abundance Human population density – 1994 Image from Wikimedia Commons

Abundance & Geographic Range Puma (previously Felis) concolor Photo & geographic range map from Wikimedia Commons

Abundance & Geographic Range Dionaea muscipula Endemic to Carolinas; native range is within 60 -mile radius of Wilmington, N. C. Video & geographic range map from Wikimedia Commons

Relative Abundance Most species are rare and geographically restricted “Species in the upper left cube at the front exhibit no component of rarity. Those at the lower back right have all three components of rarity: small geographic range, narrow habitat breadth and low local density” Habitat (niche) breadth Deborah Rabinowitz identified 7 forms of rarity Geographic range Image from Ricklefs (2000) TREE, based on original concept in Rabinowitz (1981) l ca ce o L an re d un whe r ab e n o re – m o (so mm re ra tive co he na ge) ryw the ran e ev ithin phic w gra o ge

What is an Invidividual? Genets – single genetic indiv. ; best focus for evolutionary questions Ramets – actually or potentially independent members of a genet; clones; best focus for how (semi-)independent physiological units compete Photo of the many ramets of a single genet of a dune plant from Wikimedia Commons

Dynamics Neither distributions nor abundances are static Burmese python was introduced from Southeast Asia into South Florida; its North American range (as an exotic, non-native, invasive species) has been expanding ever since Native range Introduced range Maps & photo of American alligator consuming a Burmese python from Wikimedia Commons

Dynamics Neither distributions nor abundances are static Passenger pigeons went extinct when Martha (the very last individual) died on Sept. 1, 1914 K. Harms photos taken at Smithsonian National Museum of Natural History, Washington, D. C.

Dispersal Links Populations Natal dispersal Other dispersal (among breeding sites, foraging patches, etc. ) Migration Migratory black-throated blue warbler Photo from Wikimedia Commons; Rubenstein et al. (2002) Science, Figs. 1 & 2

Distribution & Abundance are limited by Habitat Suitability, History & Dispersal Why are there no camelids in the Rain Forest Biome? Range map & photos of extant camelids from Wikimedia Commons

Distribution & Abundance are limited by Habitat Suitability, History & Dispersal Why are there no camelids in North America? Eocene Epoch – 56 to 33. 9 mya Examples of N. Am. Pleistocene Epoch megafauna (incl. Camelops) that went extinct ~ 10, 000 yr ago Map from Wikimedia Commons; image from http: //www. jqjacobs. net/anthro/paleoamericans. html

Dispersion Patterns What mechanisms could cause each of these patterns? Clumped Random Regular (over-dispersed)

Dispersion Patterns Index of Dispersion (Variance-to-Mean Ratio) 2 D= D>1 D 1 D<1

Dispersion Patterns Scale of Focus At smaller scale D>1 At larger scale D<1

Methods Area-based counts – random or stratified random placement of many replicate plots, quadrats or transects; (average count/area) * total area = population estimate Photo of random quadrat placement from http: //midlandsconservanciesforum. wordpress. com/2013/01/10/gareths-news-on-bsp/

Methods Distance methods – employ detection probability functions (one for each species or habitat) to weight observations & calculate population estimates E. g. , line transect of length, L d 2 d 1 d 3 E. g. , point sampling for a period of time, t d 2 d 1 d 3

Methods Mark-recapture studies M 1 = # of individuals caught & marked on 1 st occasion N = # of unknown individuals in the population R = # of marked individuals caught on 2 nd occasion M 2 = # of individuals caught on 2 nd occasion M 1 / N = R / M 2 N = (M 1 M 2) / R Photo of wing-tagged frigatebird from Wikimedia Commons

Methods Ecological niche-modeling An analysis with a sense of humor: ENMs for Bigfoot / Sasquatch 551 reported sightings & auditory detections; 95 reported footprints Maximum entropy niche modeling approach implemented in software MAXENT Environmental data layers for 9 BIOCLIM variables in WORLDCLIM data set: annual mean temp. ; mean diurnal range; isothermality (mean diurnal range / annual range); temp. annual range; mean temp. of wettest quarter; mean temp. of driest quarter; precip. seasonality; precip. of warmest quarter; precip. of coldest quarter Lozier et al. (2009) J. Biogeogr. ; Fig. 1

Methods Ecological niche-modeling Predicted range under current climate Lozier et al. (2009) J. Biogeogr. ; Fig. 2 Predicted range under doubled [CO 2] “convincing environmentally predicted distributions… can be generated from questionable site-occurrence data” (Lozier et al. 2009)

Methods Ecological niche-modeling Predicted range under current climate Lozier et al. (2009) J. Biogeogr. ; Fig. 2 Predicted range of American black bear using the same procedure “many [Bigfoot] sightings… may be cases of mistaken identity” (Lozier et al. 2009)