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)
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
Recognise each other for the purpose of mating and reproduction
Linked to features used to recognise mates
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
200-2000 species a year
10,000-100,000 species a year
Extinction comes after
Decrease in poppulation size
Decrease in population distribution
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 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.
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
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.
the presence in or introduction into the environment of a substance which has harmful or poisonous effects.