Biodiversity and Cladistics quiz

What is the definition of a species?

A group of organisms that can breed and produce fertile offspring

How were species originally named?

A binomial nomenclature system that puts genus first, then species

What are some problems with the biological species concept?

• hard to differentiate between a population and a species

• some organisms look very similar, but can’t interbreed

• asexually reproducing organisms don’t apply

• bacteria that show horizontal gene transfer don’t apply

What is speciation? 

The creation of new species, occurring at the population level

Can an organism interbreed with an organism with a different number of chromosomes?

No, chromosome number is a fundamental characteristic of a species

How do chromosome numbers change?

Chromosomes can split or fuse together (very rare, slow process)

What is a karyotype?

Types of chromosomes of species

What is a karyogram?

Image showing karyotype, which shows sex and chromosomal differences 

How is a karyogram done?

• Chromosomes are most visible during mitosis

• Cells stained and put on slide

• Cells burst to spread chromosomes 

• Chromosomes arranged 

What factors are chromosomes arranged by in a karyogram?

Banding pattern, size, and position of the centromere

What is a genome?

All the genetic material in an organism

What is a gene?

A length of DNA

How can you tell the differences between populations based on genes?

Differences in base Paris show divergence between populations (some genes are the same because of their vital function)

If a species has a large genome, does that mean it has lots of genes?

No

What is genome sequencing?

Understanding all of the genes in an organism

• Human Genome Project: completed in 2003

• Earth Biogenome Project: sequence all known species (goal to protect biodiversity and prevent disease)

What is a DNA barcode?

Short sections of DNA distinct enough to ID species, scientists can IDa species based off of small pieces of tissue in environment 

What is a dichotomous key? 

• made to identify species within in a group

• numbered species of pair descriptions (features clearly visible) 

• each pair leads to another pair/identification 

What is morphological classification?

hierarchical classification based on morphology

What is a clade?

Every organism evolved from a common ancestor included in same taxonomic group

What is a synapomorphy?

A trait that a clade of organisms have in common with the shared ancestor 

How are clades made?

Use biochemical evidence, like DNA and amino acid sequences

How do you determined when a clade diverged from the common ancestor? 

• Difference in genes accumulate gradually over time

• Assuming mutations happen at a constant rate, we can estimate time since 2 species diverged based on number of differences between them

How are cladograms made?

• Base sequences of gene or amino acid sequences of proteins used in constructing cladograms

• Differences can be used to calculate how long ago species diverged

• Computers do sequence analysis, looks for simplest solution

How do you analyze cladograms?

• Terminal branches represent individual clades

• Branching points called nodes (hypothetical common ancestor)

• Root is base of the cladogram

What are some examples of species being reclassified using cladistics? 

• Figwort family (plants that looked very similar, but were hugely reclassified)

• Mustelidae (weasels, badgers, and otters)

What are the 3 domains of life based on rRNA base sequences

Eukaryotes, Archaea, and Bacteria

How many mass extinction events have occurred?

5

How has biodiversity changed over time?

Biodiversity has increased at an exponential rate since the last mass extinction events, slowing down

What are the causes of anthropogenic species extinction?

• Overharvesting (hunting, harvesting, logging, and fishing)

• Habitat destruction (natural habitats destroyed for agriculture and the building of towns and cities) 

• Invasive Species (kill endemic species through predation, disease, or resource competition; could also cause endemic species extinction if they interbreed)

• Pollution (waste from fossil fuels, agriculture, mining, oil extraction, and pharmaceuticals) 

• Climate Change (rapid changes in temperature, rainfall, snow cover, ect. prevent species from adapting) 

What are the causes of ecosystem loss?

• Land-use change for agricultural expansion

• Urbanization (natural ecosystems cleared to build infastructure)

• Overexploitation (overharvesting, overhunting, ect.)

• Mining and smelting 

• Building of dams and extraction of water for irrigation 

• Drainage or diversion of water for human uses (affects swamps and wetlands)

• Leaching of fertilizers into rivers and lakes causes eutrophication 

• Climate Change 

What is the evidence for the biodiversity crisis?

• Population size of a species

• Range of species

• Diversity of species in an ecosystem

• Richness and evenness of biodiversity in an ecosystem

• Area occupied by an ecosystem 

What are the in situ methods to solve the biodiversity crisis?

Conserve species in their natural habitats

• attempt to leave areas of the earth in pristine wilderness

What are the ex situ methods to solve the biodiversity crisis? 

Preserve species outside of its natural habitat 

• putting them in a zoo

• long term storage of organic material (to be propagated in the future), germplasm

What are the advantages of in situ conservation?

• Ensures species live in environments they’re adapted to

• Allows them to interact with other species

• Behavior patterns remain normal

What are the advantages of ex situ conservation?

• relocation for species is justified when it is no longer safe for them to remain in their natural habitat 

What are the EDGE qualifications for species that get the most conservation attention? 

• Does the species have few or no close relatives?

• Is the species in danger of extinction because all of its remaining populations are threatened?