Bio Exam #2

Phylogeny – Evolutionary Tree

-Evolutionary trees are HYPOTHESISES represent the most plausible scenarios in evolution using….- advancements in DNA technology are changing everything

basal taxon- a lineage that diverges early in the history of the group, originating close to the root of the phylogentic tree AND REMAINS UNBRANCHED

identify transitions/evolutionary modifications

derived characteristics/traits- features that differ from ancestral form appearing later in a lineages evolution

outgroup- more distantly related group that serves as a reference group when determining the evolutionary relationships of the ingroup

how to use T-score to get p-value

• what a significant result is

• what a significant result tells us

-you need to know the degrees of freedom. you can calculate it by n-1 where n is the sample size

-one or two tailed t test- then you use the table

a signficiant result in a t test means THE DIFFERENCE BETWEEN GROUPS IS UNLIKELY DUE TO RANDOM CHANCE- TRUE DIFFERENCE EXISTS IN THE POPULATION_ STRONG EVIDENCE AGAINST THE NULL HYPOTHESIS

Biological community

an interacting assemblage of different species POPULATIONS inhabiting the same habitat/a common location at the same time

Biological fitness

an organisms ability to surive reproduce and pass its genes to the next generation- RATHER THAN JUST PHYSICAL STRENGTH OR SPEED MESSURES REPRODCUTIVE SUCCESS

Homologous vs analogous structures

Homologous structures- SHARE A COMMON ANCESTOR and SIMILAR INTERNAL ANATOMY INDICATING DIVERGENT EVOLUTION

ex. human arm vs whale flipper

analogous structures- SIMILAR FUNCTIONS BUT DIFF ANCESTRAL ORGINGINS

ex. bird and insect wing, bird wing vs bat wing

Adaptive Radiation

An evolutionary process where a single ancestral species quickly diversifies into many new species, each specially adapted to exploit different ecological niches, triggered by new oppotunity such as empty habitats or new resources

example- darwins finches- single ancestral species from south america evolved in 15 different birds

Stickleback fish info

In oceans stickleback fish evolve with heavy pelvic spines which protect them against predators- anti swallowing mechanism, armed plating against predators- spines are favored in environments w large predators

In freshwater lakes stickleback fish loose their spines due to a lack of ocean type predators and dragonfly larve which prey on them by grabbing onto their spines

The fossil record for sticklebacks tells us that LOSS OF PELVIC SPINES HAS HAPPENED REPEATDELY IN SEPERATE POPULATIONS

NOT

• sticklebacks w/out spines are different species than ancestors this is untrue

• not that there has been a gradual reduction in spines over time this is untrue

Community Composition

Which species are present in a community, sets up competition and in turn competition can determine community composition

Interference competition

Direct, aggressive interaction- fighting, territoriality, chemical inhibition, that prevents rivals from accessing resources- like caterpillars pushing each other off of a leaf they are both trying to eat

Exploitation Competition

Indirect competition, where competitors deplete shared resources faster than others can, reducing availability without direct contact

Competition

Affects both/all species competing over a SHARED resource that is limited, the species competiting need the resource, for growth, reproduction, survival

Obligate mutalism

two species completely dependent on each other for survival

facultative mutualism

a flexible relationship where species mutually benefit from each other but can survive independently

trophic mutualism

Specialized mutualism where nutrients and energy are shared- ex. bacteria in the gut microbiome

Defensive mutualism

one partner receives food or shelter in exchange for defending the other from predators or parasites

dispersive mutualism

involves animals transporting pollen or seeds for plants in return for food

Commensialism

+/0 relationship where one organism benefits while the other is neither helped nor harmed ex. barnacles on whales

Amensalism

-/0 one species causes harm while gaining nothing

• Physical suppression- larger more dominant organism harms another by physical presence- ex. cattle trampling plants, insects, wide trees shading out smaller plants

• Antibiosis (chemical inhibition)- one organism produces chemicals that harm another. Ex. penicillium mold produces penicillin which kills bacteria

Positive Control vs Negative control

-a positive control is designed to produce a known, expected result, CONFIRMING that the experiment is working properly

-Negative control- designed to produce NO RESULT, ensuring that results are due to treatment and not external factors or contamination

Null hypothesis vs alternate hypothesis

Null hypothesis- states that there is no effect, relationship, or difference between variables, assuming that status quo

Alternate hypothesis- contradicts the null hypothesis proposing there is a significant different or effect that the researcher seeks to prove

de Wit Replacement Series

-An experimental design technique used to examine RESOURCE USE and PRODUCTIVITY between competing species

• Used to analyze intra- vs interspecific competition- it’s primary goal is to determine the competitive ability of a species and evaluate dynamics between species and within a species by analyzing the yield produced from the cultures

  • shows if one species can outcompete another

• Monocultures paired with mixed cultures

• A constant TOTAL DESNITY is used but the frequency of the two species is changed: 100:0, 75:25, 50:50, 25:75, 0:100

Monoculture vs mixed culture

Monoculture- only growing/cultivating one species

mixed culture- multiple species are grown/cultivated

Destructive Sampling

(plants) the permanent removal, alteration or consumption of plant material

-A research method that involves the permanent removal, alteration, or damage of a specimen to obtain scientific data.

Value of research museum collections

-allows for the detection of change-loss of a species, biodiversity, emergence of pathogens and diseases, make overall deductions about the extent/impact/progression of environmental change and climate change

-allows people to be able to compare historical specimens with modern ones researchers can track species population declines, range shifts? and altered life cycles which allow scientists to RECONSTRUCT HISTORICAL CLIMATES HABITATS AND ENVIORMENTAL STRESSORS

• Species range shifts- comparing historical collection locations to current species distributions to help identify if species have moved due to changing temperatures

-Allows scientists to track GENETIC SHIFTS in a species- DNA extracted from old species samples helps scientists understand past population dynamics GENETIC BOTTLENECKS and how species adapted genetically to environmental shifts over time

Ecological diversity

refers to the variety of different ecosystems such as forests, deserts, etc across an area

Biodiversity

-Biodiversity is an umbrella term that covers the variety of all life on earth including genetic diversity, species diversity and ecological diversity

• think variation in genes, species and ecosystems for all living things

Genetic Diversity/ Importance of genetic diversity

genetic diversity- the total number of genetic characteristics in the genetic makeup of a species

• key indicator of a populations health, adaptability and long-term survival prospects

• High genetic diversity means a species can adapt to changing environments, there is a strong evolutionary potential within the population and a lot of raw genetic material to work with

• while low genetic diversity in a species- often due to population bottlenecks- indicates a species is vulnerable to extinction

  • A genetically diverse population is more resistant to pathogens, less susceptible to genetic disorders, more able to withstand unforeseen environmental shifts

Species Diversity (richness and evenness)

Species richness- total number of different species present within a defined ecological community, landscape or region, counting species without considering their abundance or relative distribution

• Higher counts indicate greater richness, often signaling a healthier, more complex ecosystem

Species evenness- an ecological measure of how close in numbers each species in an environment is. Indicates if a community is dominated by one species or if they all have relatively even population sizes

• High evenness means species are equally distributed while low evenness means species are unequally distributed

Habitat Diversity

Habitat diversity refers to the variety of different ecosystems, ecological niches, and physical environments (forests, wetlands, grasslands, deserts, etc) within a specific geographic area

• Key indicator of ecological health as a greater variety of habitats supports a higher biodiversity, offering more opportunities for different species to survive

larger factors that can influence the range of a species

• Species ranges are primarily determined by:

  • climatic conditions like temperature and precipitation

  • Physical geological barriers- mountains, oceans

  • ecological interactions like food availability

  • human induced habitat changes

How human activity can change biogeography (effect of invasive species)

-global trade and transport vectors are prime pathways for invasive species

-intentional introductions- humans frequently introduce species for agriculture, pest control, or ornamental purposes that escape into the wild and infiltrate natural ecosystems

-Habitat alteration- deforestation, creation of cities create windows of opportunity for invasive species to establish themselves

-the breaking of natural geographic barriers

Biogeography

• The pattern of species distribution both worldwide and local

• Includes history of species distribution

  • continental drift is vital to understanding how species became distributed

  • Climate affects species distribution both historically and locally- earth has been hotter and cooler, winds and currents change as land moves

Assemblage

refers to a group of different species populations that co-occur in the same space and time, interacting in a specific habitat

MICROevolution

species change from one generation to the next

MACROevolution

Radically new life forms derive from older life forms over time- thousands to millions of years