APES UNIT 2

GRRRR LOCK IN.

Biodiversity

• variety of all life forms on earth.

Genetic diversity:

measure of genetic variation among individuals of a population. High genetic diversity benefits the long term persistence of a species because they can better resist environmental changes (ex: bananas and the pathogen).

Larger species usually have

higher genetic diversity

Population Bottleneck:

 a larger population declines in numbers quickly, reducing genetic diversity of living individuals.

Species diversity:

• number of species in a region or particular ecosystem. A higher number of species leads to more productive and resilient ecosystems (higher GPP).

Habitat Diversity:

• variety of habitats that exist in a given ecosystem. When habitats are lost due to human activity, specialists are also lost because they have evolved adaptations to that specific region. Only when habitat is loss is too big that generalist species will fall, since they can adapt to many areas 

Specialists

•  can only live in a narrow range of biotic and abiotic conditions.

Generalists

• can live in a wide range of biotic and abiotic conditions.

Ecosystem Diversity:

variety of ecosystems that exist in a given region.

Species richness:

 total number of species

Species Evenness:

relative proportion of individuals when compared to the total.

Ecosystem services:

• processes which life- supporting resources are produced. 

  • Are worth over 125 trillion dollars per year.

Provision

•  Goods that humans can use directly

  • Lumber, crops, furs, etc. 

Regulating services

•  natural ecosystems that regulate environmental conditions. It increases the resilience of an ecosystem, allowing for it to exist in the future. Ties in with species diversity and quantity because more species who do the same service helps with that.

•  Trees and ocean removing carbon from the atmosphere.

Support systems

• support services that would be hard or costly for humans to generate. 

  • Pollination, filtering harmful pathogens from water (hydrologic cycle)

Cultural Services

cultural or aesthetic benefits of nature.

Aquaculture

cultivation of fish and seaweed. It decreases species diversity due to the focus on specific species, and also decreases the total number of the species due to them being fished out.

Island Biogeography

study on how species are distributed, and how they interact, in islands.

Larger islands house

•  more species than smaller islands.

Migrating species are more likely to

• find larger islands than smaller islands

Larger islands just support more species than smaller ones.

• Larger islands also support larger predators than smaller ones.  

• Larger islands contain more biotic and abiotic factors that can support more species.

“Islands” are not only in the ocean

but also represent isolated habitats, such as wet lands, that are scattered within other habitats.

Species-area curve

•  a description of how the number of species in an island depends on the size of the island (more area = more species). 

  • Actual graph: y = mx +b 

  • Linearized graph: log(y) =  mlog(x) + lob(b)

Colonization & distance

species that come into the island. The closer the distance the higher the rate of colonization.

Model for island biogeography

predicts the total number of species in an island based on the size and distance from mainland (shown as species richness and colonization rate).

Realized Niche

fundamental niche + biotic factors.

Geographic Range

• area in the world where a species lives. 

  • Since species are adapted to the environment they evolved in, environmental disruptions cause their distribution to be altered.

    • This applies to right now with global warming. 

    • It is also important to consider the mobility of species in this process, both morphologically and human impact (cities in the way, highways, etc).

Extinction

• species that cannot adapt to changes in environment, or moved, are driven to extinction

Mass Extinction

large amounts of species have gone extinct in short periods of time. We have had five mass extinctions and are facing the sixth currently.

Periodic disruption:

•  occurs regularly, such as the cycle of day and night or the moon cycle over a month.

Episodic disruption:

• occurring somewhat regularly, such as the cycle of high and low rain every 5-10 years. 

Random disruption

occurring with no pattern whatsoever, such as hurricanes and volcanic eruptions.

Disruptions in general

• they can deeply affect an environment and cause large effects, but the probability of them occurring in the same place twice is low. Other large ones are more regularly hitting the same place. Changes with small spatial reach are also of small duration (thunderstorms for hours and geologic rise of a mountain for millenia). 

  • Ex, we have many natural disasters every year, but most of them don't hit the same place twice in repeating years. 

Resistance

How much a disruption affects the flow of energy

Resilience

how quickly an environment can “bounce back” after a disruption.

Species composition:

• foraminifera, a small hard shelled protist species whose shells resist decay after death. Since each species prefers a specific temperature, they can use layers of them in the bottom of the ocean to estimate the temperature. 

Air bubbles in ancient ice:

•  compressed ice carries gas from different time periods. Thus, scientists can melt ice associated with a time period and measure greenhouse gas levels 

• Analyzing fossils with marine traits in different regions also indicates where and how much water was present in different areas.

Intermediate disturbance hypothesis:

• hypothesis that environments where ecosystems have intermediate levels of disturbance will have more diversity than other environments

Low levels:

 too much competition between species due to lax environment

High levels:

• eliminate most species except those developed to resist these situations.

Evolution

•  a change in the genetic makeup of a species over time

Genetic mutations:

•  are the key to this variation, they are sometimes passed down to the next generation. If it continues being passed down, it increases genetic variation. The larger the population the more likely mutations are to happen, and the more favorable mutations there are the more likely evolution is to happen. 

Recombination

 a piece of one chromosome breaks off and attaches to another chromosome, creating new combinations (does not create new genes).

Microevolution

• evolution at the population level

Macroevolution

• evolution that gives rise to new species, genera, family, classes, or even phylum

Evolution by artificial selection:

• microevolution, usually by humans, looking for selected traits in animals or plants. They still remain the same species regardless of all the changes. Usually is much faster.

Evolution by natural selection:

•  environment decides which beings survive and reproduce. Usually it is very slow. 

Fitness

• : individual’s ability to survive and reproduce.

Adaptation

•  a trait that improves an individual’s fitness. 

Evolution by random processes:

• the processes that change the genetic composition of species over time, but the changes are not related to the fitness of individuals.

Gene flow:

•  same species but different individuals come together, altering the genetic composition of both populations because they have different characteristics and alleles. 

Genetic drift

• change in genetic composition due to breeding. Random mating can cause unique traits to not be passed down simply because of random breeding. Those phenotypes are lost. 

  • More common in smaller populations

Founder effect

•  few individuals of a larger population are isolated from it, being imposed to different biotic and abiotic conditions, causing genetic variation to vary between isolated and non-isolated groups. 

Allopatric speciation

• geographic isolation. Species are isolated from others in a way it can't interact, populations evolve independently too much to the point where they cannot interbreed anymore. 

  • Darwin’s finches. 

Sympatric speciation:

•  evolution of one species into two without geographic isolation. Usually happens due to polyploidy (increased amount of chromosomes from two, making them non-diploid.

Genetically modified organism (GMO):

organism produced by copying genes that are desirable and inserting them into another species or organism.

Ecological succession:

• the predictable replacement of one species by another over time. It increases species richness, thus increasing produced biomass, thus increasing productivity. 

Primary succession

• ecological succession happening in places with no soil, just bare rock. 

  • Pioneer species algae, lichens, and mosses. Organisms that can survive on little to no soil, and usually have a short lifespan. They excrete acids that break down the rock’s nutrients, and when they die, they enrich that leftover eroded rock, allowing for layers of nutrients to build up for bigger life forms.

ORDER

Order: exposed rock, pioneers, annual wildflowers, perineal wildflowers/grasses, shrubs, aspen/cherry/young pine, beech and maple broadleaf.

Secondary succession

 occurs in areas that were disturbed but still have soil. Starts with perennial wildflowers and grasses.

Climax community

• final stage of ecological succession.