Lecture 21-22 (Case Studies) Flashcards

Question

Why are islands especially vulnerable to invaders?

Answer 1

Loss of defenses: species have evolved with the absence of predators - lack of large predators on islands can also result in changes in island species - no reason to maintain energetically expensive defenses if there are no more predators to defend yourself from --> leads to the loss of defenses compared to mainland counterparts. Vulnerability to novel pests/pathogens - absence of many pest and pathogen lineages present in the home ranges of invasive species (open niches that can be filled)

Answer 2

Biocontrol

Answer 3

Many islands still volcanically active --> cycle of destruction from lava flows and regrowth - Volcanic activity is destructive in the short run, but provides land area and minerals for plant growth in the long run. Age of island also influences terrestrial and marine ecosystems --> nutrient availability in both systems changes over the life of an island - Soils eroded to ocean brings minerals to marine environments - As terrestrial biodiversity decreases, marine biodiversity increases

Answer 4

Complete destruction of existing flora and any fauna which is not able to move out of the way Mineral rich substrate remains after lava flow Lichens, ferns and mosses begin to colonize the volcanic substrate - seed plants in cracks - contributes to soil formation --> gives rise to more plants

Answer 5

At the beginning, nutrients are locked in rocks - not a lot of vegetation As more plants begin to colonize the substrate, promotes soil formation and the growth of more vegetation - plants begin to grow and replete with new nutrients At the peak, soil is fertile and breaks down with weathering Biomass begins to decline toward the end since nutrient supply is exhausted

Answer 6

Dry land connection between North and South America (3 million years ago) First complete link between the Americas since the breakup of Pangea Physical changes included tectonic movements, ocean circulation, climatic change

Answer 7

Smaller plates buffered the collision (multiple plates moving in different directions) Formation of isthmus occurred gradually

Answer 8

Circum-tropical circulation of warm water is blocked Warm current deflected north in Atlantic (Gulf Stream) Gulf Stream deflects Labrador Current Humboldt Current flows north on Pacific side. Before, the ocean circulation had 3 passages (any precipitation could fall in warm areas as rain) After, warm circulation/current gets forced upwards and creates the Gulf stream - Have warm and cold bodies meeting further north - Precipitation has much higher chance of falling as snow --> can create glaciation

Answer 9

Increased temperature difference between warm Caribbean/Gulf of Mexico and cool Pacific Deflection of Gulf Stream increases moisture in northern latitudes

Answer 10

Islands are dry land Dry land is surrounded by shallower water Evidence for shallow water in past Fossil remains of many species of shallow water in sediments in Caribbean - Can date these fossils to see when shallow water existed

Answer 11

Land bridge as barrier to dispersal for marine organisms Land bridge as a corridor for dispersal for land organisms

Answer 12

Climatic changes Geological changes lead to subsequent changes in distribution - ecology

Answer 13

As soon as Isthmus closed, wind that was blowing across pushed water away on the Pacific side - pulled water in from deep and brought up nutrients (trade winds, upwelling and nutrients) - can draw inferences with fossils associated with this (fossils and shell formations)

Answer 14

Isolation of populations of marine invertebrates Related species in several groups isolated across isthmus - ex. snapping shrimp, marine snails, foraminiferans --> leads to speciation because there are different environmental conditions (accumulation of genetic differences, phenotypic differences)

Answer 15

Pacific: - water is much deeper - periodic upwelling - very fast moving pelagic productive system (due to high nutrient availability) Caribbean - caribbean and atlantic plate makes more shallow and protected water - lower in available nutrient content - more coral reefs - interactions between abiotic and biotic (biotic created new environmental conditions for new organisms)

Answer 16

Pacific: - production - high nutrient content but sporadic - pelagic Caribbean: - construction - low nutrient content - corals, mangroves, seagrasses (slow growing, then creates additional habitats and protection/stability)

Answer 17

the great american biotic interchange

Answer 18

Both continents had diverse fauna of large mammals, birds, etc. filling all the usual terrestrial niches - large and small predators - large herbivores - grazers and browsers - small herbivores - scavengers Savanna, grassland, forest specialists

Answer 19

They were separated for a long time --> no gene exchange, have entirely different organisms evolving in parallel in these different areas All of the different type of niches were filled by animals with similar kind of traits (convergent evolution) Even though genetic pathways (and evolutionary history) is completely different, selective pressure creates similar traits

Answer 20

Unrelated species subject to similar environmental and ecological conditions Selection pressures drives evolution in similar directions Species come to resemble each other Many examples in North and South America prior to connection - saber-toothed cats in North vs. saber-toothed marsupials in South - Camels in North vs. lipopterns in South (large browsers) - Rhinos in North vs. toxodontids in South (large grazers)

Answer 21

Successive waves of interchange Heralds: early colonizers (island hopping) Legions: mains invasion group (walkers and crawlers)

Answer 22

(moved south) Shrews, rabbits, mice, squirrels, bears, horses, etc... - Many of these later became extinct in the North Several carnivores also moved south Large cats and dogs --> both families are now more diverse there than anywhere Many North American groups became quite diverse in South America - Some became extinct during Pleistocene

Answer 23

Animals moving from South to North armadillos, sloths, capybaras, manatees, etc.

Answer 24

Large flightless predators Dominant in South American savannas Later dispersed to North America Range of sizes and habits in South America

Answer 25

At least 50% of South American mammals are descendants of ancestors that came from North America Several extinctions in South American mammal fauna - competition, predation Birds, reptiles, amphibians not as affected - South American birds unique - high diversity and endemism - few shared reptiles or amphibians

Answer 26

Several groups have continued to move across isthmus since first establishment Diverse in one continent, with few species on other side of isthmus Southern groups: iguanas, hummingbirds Northern groups: salamanders

Answer 27

Flora and fauna of North and South America are still quite distinctive Replacement of the physical barrier (salt water) with an ecological barrier

Answer 28

Rainforest, cloud forest

Answer 29

Desert and shrub forest

Answer 30

No longer a complete barrier --> Panama Canal connects Atlantic to Pacific freshwater vs. saltwater --> freshwater barrier to marine organisms (26 m above sea level) - ships move into freshwater through locks - 200+ million liters of freshwater used up per ship --> a LOT of water (although it is recycled, it becomes very saline)

Answer 31

Rainforest produces more water than developed land Buffer zone of protected land on either side of canal provides freshwater, but also protects habitats and species Increasing pressure for crops, development Widening canal requires bigger drainage area

Lecture 21-22 (Case Studies) Flashcards

(55 cards)