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Biological Species
A group of interbreeding natural population that do not (usually) successfully mate or reproduce with other such groups (which occupy a specific niche) |
Asexual Species |
Fragmentation - Starfish |
An arm is removed, and grows into a new Starfish. Where the arm that was removed, a new arm will regrow on the old body. |
Budding - Yeast cells |
Buds come off of their organisms which, are genetically identical to them. |
When relatives mate |
Two different, yet closely relating species mate |
Horse + Donkey = Mules (mostly infertile) |
Russet-backed Thrush + Olived-backed Thrush (fertile offspring) |
Cohesion Species
Small group of cohesive individuals that share intrinsic cohesive mechanisms. |
Genetic cohesive mechanisms |
Gene flow and stabilising selection function to maintain species integrity |
Ecological cohesive mechanisms |
Abundance, demographic stability, strengths of interactions with other species |
Potential for genetic and/or demographic exchangeability. |
Downplays hybridisation (i.e. what separates species) |
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Ecological Species
Lineages that occupy and adaptive zone different in some way from that of any other lineage within its range, and which evoles separately from all other lineages outside its range |
Common ancestor but now diverged Ecological competition within its own species |
Adapting to individual niches |
Recognition Species
Recognise each other for the purpose of mating and reproduction |
Linked to features used to recognise mates |
White peacock |
Females would not recognise him as the same speices. They may not mate with him. |
The Western meadowlark and Eastern meadowlark |
Look very similar but have a different song. They do not breed as their distinct song prevents them from recognising each other. |
The sixth mass extinction
Earth appears to be undergoing a 6th mass extintion |
Extinction is occurring faster than "background extintion" (which occurs between the mass extinction events) |
1 species extinct per 1 million species each year |
Rate of between 10-10,000 times faster than background extinction |
Recent data |
Lower estimate |
200-2000 species a year |
Upper estimate |
10,000-100,000 species a year |
Extinction comes after |
Decrease in poppulation size |
Decrease in population distribution |
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Hard to know..
We don't know how many species exist |
Impossible to estimate |
>Take samples and extrapolate up >Look at patterns in identication rates >Look at ratio - such as 1:6 vascular plants to fungi |
Bias towards species |
>Charismatic >Larger >Common species |
Least known or described |
>Fungi >Viruses >Bacteria |
1.5 million catalogued so far |
100k well known |
Eastimated to be 3-10 million species globally |
Anthropogenic causes
Anthropogenic hazards are hazards caused by human action or inaction. They are contrasted with natural hazards. Anthropogenic hazards may adversely affect humans, other organisms, biomes, and ecosystems. |
land development |
is altering the landscape in any number of ways such as: Changing landforms from a natural or semi-natural state for a purpose such as agriculture or housing Subdividing real estate |
overexploitation |
the action or fact of making excessive use of a resource. |
Species translocations and introductions |
Translocation: The intentional capture and release of animals to the wild to establish, reestablish, or augment a population. |
pollution |
the presence in or introduction into the environment of a substance which has harmful or poisonous effects. |
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