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Biogeography
| List the 2 histories that shaped contemporary biotas | History of Place - environmental and geographic, extrinsic to species or lineages History of Lineage - changes intrinsic to populations, species, higher taxa |
| Define cosmopolitan species | Limits to distribution, but some species are very widely distributed **No species is completely cosmopolitan |
| Examples of Cosmopolitan | Worldwide distributions by natural means = widespread taxa: Peregrine Falcon Diverse plant genus Senecio ragworts Bat family Vespertilionidae |
| Define endemic | occurring in a particular geographic place or area |
| Define provincialism | Endemics tend to cluster in regions |
| Examples of Endemism | - Ovenbirds is endemic to South and Central America - Catfish eels are confined to Indo-Pacific region - Hierarchical endemism = Rodent family Heteromyidae |
| Rodent family Heteromyidae | Endemic to Western North America, Central America and Northernmost South America - Each of the 6 extant genera has a more restricted range |
| Explain Disjunctions | Related taxa that occur in widely separated regions - Reflect past events - Often morphologically similar and inhabit similar environments |
| What is an example of a Disjunction? | - Nothofagus (Southern Beeches) - Evergreen Southern Beeches grow in wet, cool temperature forests in South America, New Zealand, New Caledonia, New Guinea, New Britain and Australia |
| Explain 3 ways that an organism can be endemic | 1. Originated in that place and never dispersed 2. Shift entire range (shifted in locality subsequently to origination) 3. Biogeographic relict |
| Define Biogeographic Relict | Organisms now survive in only a small part of their once-expansive former range |
| Define Autochthonous Endemic | - A taxon that differentiated where it is currently found - Important in the determination of vicariance - Need confidence that the current geographic distributions of sister taxa represent their original areas of differentiation |
| Define Allochthonous Endemic | - A taxon that the origination was somewhere other than where it exists today |
| Define Distributional Congruence | - Reflects a shared history of diversification across taxonomic groups - Shared history of place, and for higher taxonomic groups, a shared history of lineage |
| Example of Distributional Congruence (land) | North American Deserts - Long been divided into 4 provinces, the Great Basin, Mojave, Sonoran, Chihuahuan based originally on pioneering floristic studies of Forest Shreve |
| Example of Distributional Congruence (organism) | North American fishes reflect major drainage systems - Congruence in patterns of endemism across different lineages of organisms = they respond similarly to geographic variation in important geological, topographic, & climatic features of Earth |
| What are Biogeographical Lines and how are they open to interpretation? | - Boundaries of Regions - Emphasis on distributional limits of different taxa - Variation in criteria used - Methodological differences |
| Why is it difficult to separate unambiguously biota between regions? | - Variability of species - Timing |
| Define Provincialism | Endemic groups are often clumped in particular regions |
| What is the relation of Provincialism to sympatric, parapatric, and allopatric | - Most closely related species tend to have overlapping (SYMPATRIC) or adjacent ranges (PARAPATRIC) within continents (or oceans) Small number of related taxa have markedly disjunct ranges (ALLOPATRIC) |
| List the several processes of disjunction that may occur across spatial or temporal scales | - Continental Drift (Tectonics) - Dispersal across barriers - Extinction of intervening groups |
| Provide examples of Disjunctions by Continental Drift | - Southern Beeches - Marsupial mammals - Frogs in Family Pepidae - aquatic tongueless frogs |
| Define Amphitropical Distributions and provide an example | Related taxa that exist at comparable north-south latitudes, but not in the equatorial tropics Example: Creosote Bush (Larrea) = more recent diversification and expansion |
| Explain Disjunctions by Plate Tectonics | The organisms ancestors occurred on pieces of the Earth's crust that were once united, but have subsequently split and drifted apart |
| Explain Disjunctions by Intervening Extinction | The organisms ancestors were once broadly distributed, but populations in the intervening areas have gone extinct, leaving isolated relicts |
| Explain Disjunctions by Dispersal | At least one lineage has dispersed a long distance from the area where its ancestor(s) originally occurred |
| List Biotic interchange | - Dispersal across barriers - Barriers become reduced or disappear |
| Explain why Provincialism persists | Combination of processes: - Continued levels (or degrees) of isolation - Recent timing or ephemeral nature of dispersal routes - Biotic resistance to invasion - Evolutionary history |
| Provide an explanation of South American isolation and New World Monkeys Hypotheses | - Isolation from 140 - 75 ma = biota diverges - Interrupted by early transient colonization (dispersal) from N. A - Early stepping stone or sweepstakes through the Caribbean region ( > 40 ma - 3.5 ma) - Rafting from afar |
| Describe the Great American Biotic Interchange (GABI) | - Isthmus closed 3.5 - 3.7 ma - More of a filter than a corridor - More Nearctic mammal taxa |
| Please explain why were northern taxa in GABI more successful in colonizing the south? | Pleistocene better migrators, predators, placental over marsupials - Northern taxa were better migrators = more taxa from Savanna biomes - Northern taxa were better prone to speciation |
| How did the Great American Biotic Interchange (GABI) have a huge impact on S American Biota? | ~half of Southern contemporary species are northern derived 10% of Northern contemporary species are southern derived |
| Provide the perspective of Stephen Jay Gould on breeding physiology, favoring northern species during GABI | Breeding physiology (placental v. marsupial) was not the driving factor that favored northern species during the GABI - Instead, northern mammals evolved through earlier extinction events associated with climate driven environmental change |
| How did favoring northern species during GABI lead to adapted species? | - Led to loss of older forms and radiations in the north of more adapted species = more competitive species |
| List the different time periods of Gould's perspective | Mid-Miocene climatic transition ~14 - 13 ma, change from forest to grasslands Late Miocene aridification ~7 - 5.3 ma, expansion of grasslands Early Pliocene cooling ~5.3 - 3.7 ma, increasing climatic oscillations |
| Describe Convergent Evolution | - Similar physical environments exert similar selective pressures on distantly related organisms = Pressure drives similar adaptive responses - confound biogeographical patterns - may occur at various biological levels - across 5 genera of rodents |
| What studies does islands have a great influence in? | On ecology, evolution and biogeography |
| How are island and insular ecosystems ideal "natural experiments" | - Well defined (geographically - boundaries) - Isolated (bounded) - Occur in replicated groups = structured, archipelagos - Relatively simple = biologically - Realistic = when compared to laboratory experiments |
| List the different types of islands | Oceanic, land bridge or continental shelf, and continental fragments |
| Describe oceanic islands | - Never connected to mainlands - Most are volcanic (Hawaiian island) |
| Describe land bridge or continental shelf islands | - Often connected to land masses during times of lower sea levels (Channel islands) |
| Describe continental fragments | - Islands that are sundered from continental plates during tectonic processes |
| Describe the Species-area relationship | - Regardless of taxonomic group or type of ecosystem, species number tends to increase with increasing area - Pattern is not linear |
| List the benefits of Larger Islands | - Greater variety of resources - Greater abundances of resources - Support larger populations = less likely to go extinct, greater variety of niches - Thus, more species |
| Describe what the Species-area relationship is shaped by | Relative Abundances - Shaped by abundances of species - Most species are rare to moderately rare - Communities contain more rare species than common ones |
| As a progressively large area is sampled, how are more individuals and more species encountered | - Rare = some of the new individuals will represent rare species that are previously not observed = presence v. absence of a species - Specialized = Diff kinds of environmental conditions get sampled that contain specialized species - Driver |
| Describe the slope of species-area is steeper for areas on islands than on larger land masses | - Rare species are prone to extinction - On continental area, populations of rare species could be maintained by dispersal - The smaller the island, the steeper the slope |
| Why do isolated islands contain fewer species than islands near continents or other large landmasses? | - Mostly due to a decline in immigration (colonists) |
| List the Caveats of Species-area relationships | - Sampling protocols (size of areas, nested or not, desired comparisons) - Characteristics of focal taxa (dispersal ability, reproduction, niche) - Characteristics of the islands |
| List the Caveats of Species-isolation relationship | - Difficult to measure isolation that reflects likelihood of immigration - Dispersal ability and patterns of focal taxa - Ocean and wind currents - Impacts of sea level changes over time on island isolation |
| List the theory found in the 1960s in relation to Island Biogeography and the ecologists | 1960s - Robert MacArthur, Edward O. Wilson - Equilibrium Model of Island Biogeography |
| Describe the Island Biota and its influences | - Influenced by dispersal ability of organisms - Arriving species either found adequate resources and survived or failed to join the biota - Biotas reflected fixed availability of resources (niches) |
| Describe biotas | All living organisms within a particular region or area |
| List the 3 interrelated phenomena of island biota and what they're driven by | - Species-area - Species-isolation - Species turnover - Driven by: Extinction of species on islands, Replacement (colonization) by new colonizing species |
| How is Island Biota a dynamic equilibrium? | The number of species on an island is a dynamic equilibrium between opposing rates of immigration and extinction |
| List the Prediction from the Island Biotas models | - Species numbers: Ssf < Ssn ~ Slf < Sln - Turnover rates: Tsn > Tsf ~ Tln > Tlf - Rates of return of equilibrium is perturbed - Island biota area dynamic in composition of species but the number of species is predictable |
| Describe the meaningfulness of the Island Biota Model | - Provided testable prediction - Considered heuristic (involving or enabling discovery or problem-solving through methods of experimentation, evaluation and trial and error) |
| List the hesitations of the Meaningfulness of the Island Biota Model | - Simplified Assumptions = limited explanatory power that of explaining patterns of species richness on islands - Driving forces for island biota appear to be more complex than those assumed by the model |
| List the greatest influence on extinction rates and what the relation describes | - Island size has the greatest influence on extinction rates - Species-area relationship |
| List the greatest influence on immigration rates and what the relation describes | - Island isolation has the greatest influence on immigration rates - Species-isolation relationship |
| Even at equilibrium, how is species composition dynamic? | - Species turnover - Species composition is dynamic (immigration and extinction rates) |
| List the factors that tested the Equilibrium Model | Simberloff and Willson 1969 - 1970 - Islets - Limited isolation - Killed arthropods - Monitored recovery |
| Explain the results of the Equilibrium Model Test of Simberloff and Willson | - Rapid recolonization of less than a year - Overshoot: species richness appeared to overshoot the initial values before relaxing towards initial values - High rate of species turnover = expected given the mainland was close |
| Explain the Study of Montane Refugia by James Brown 1971, 1978 | - Boreal forest on mountain tops in Great Basin - Sources for species = surrounding mountain ranges - Expectation for mammals = an equilibrium model to fit patterns for small non-volant mammals adapted to boreal (high altitude) conditions |
| Explain the Results of the Study of Montane Refugia | - Number of Montane mammal species increased with the area of boreal forest = species-area relationship - Distance to source area = No detectable effect |
| Explain the Faunal Relaxation Model | Montane mammals on mountain tops as Pleistocene Relicts |
| Describe the Study of Birds in Montane Refugia in Great Basin | - No detectable effect of distance to source area = Birds were seen flying between mountain ranges - Weak species-area association = smaller mountains simply lacked sufficient area of suitable habitat for some species |
| Describe the Assessment of montane mammals in Sky Islands, AZ & NM | - Faunal relaxation model does not fit for montane mammals - Mountains separated - More of a filter barrier rather than hard barriers |
| How does island size likely effect immigration? | - Larger islands tend to attract (or intercept) more immigrations - Target Effect Area - Equilibrium model assumes island area (size) has no impact of immigration |
| Describe the Rescue Effect and how immigration rates likely effect extinctions | - Immigration of new individuals of an already existing species on the island may sustain the population - Extrication rates should be lower on islands with HIGHER immigration rates |
| Describe the Speciation on islands | - Common on islands - Speciation is recognized by the equilibrium model delta S = M + G - D S = # of species, M = immigration, G = Speciation, D = Extinction - Implications: At Equilibrium: immigration (M) + Speciation (G) = Extinction (D) |
| List the hypothesized model of Cryptic Vicariance in the historical assembly of a Baja Peninsular Desert Biota: Late Pleistocene Dispersal | Late Pleistocene Dispersal - Little variation - Under this model, the peninsular and western continental deserts (Mojave and Sonoran deserts) should have a high number of taxa that exhibit little or no genetic differentiation across the regions |
| List the hypothesize model of Cryptic Vicariance covering Late Neogene Vicariance | - Under this model, populations of particular species on either side of hypothesized barriers will represent separate phylogroups |
| List the caveats of the 2 hypothesized models for Cryptic Vicariance | - The species had to be present across the region when the vicariance occurred - Enough time has past for the separated populations to have genetically diverged - Potential subsequent dispersal has not eroded the genetic signal of vicariance |
| Explain the 4 Hypothesized Vicariance Events | - Miocene (early Pliocene) extension of Southern Gulf - Pliocene seaway across the Isthmus of La Paz - Late Pliocene Northern Gulf - Northward transgression of the Sea of Cortez - Middle Pleistocene midpeninsula sea-way |
| List the Methods used for Cryptic Vicariance | - Five rodents and a toad - DNA sequencing of mtDNA - Phylogenetic analyses - Genetic divergence estimates - Fig 4: Added 6 additional species: 1 bird, 3 lizards, 1 snake, 1 rodent |
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