GENE 4950

What are species (in the real world)?

https://www.nhm.ac.uk/discover/are-neanderthals-same-species-as-us.html

In contrast to what Grant & Grant argued, most “speciation” takes a very long time - modern humans only radiated from Africa to other parts of the world around 60kya

Biological Species Concept

One of several ways that species have been defined or at least considered revolves around reproductive isolation

As we saw from the extensive (!) paper by Anja Westram et al, that is easier said than studied :)

Example: Pacific coast Barnacles

Abrupt transitions in allele/genotype frequencies in the barnacle Balanus glandula seem to coincide with an interruption in available habitat

The overall change in genomic diversity is very strong, and there are reproductive phenotypes that differ to the north and south.

Are these two species?

Sea stars Asterias forbesi (green bars) and Asterias rubens (orange) seem to have distinct but overlapping “climate envelopes”

Menti.com again

https://www.menti.com/alii23oeibkp

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Or menti.com and use the code 2542 6385

What do we think of the history of asking about “species”?

So our questions today are about reproductive isolation

1. How can it be measured in a way that can be compared among studies?
2. What kind of effort is involved in assessing it for different types of organisms, what are limiting resources?
3. How do we apply this to the idea of “what is a species?”

Organismal vs. Genetic

They distinguish between organismal (fitness-focused) evaluations of RI and genetic (how does diversity move between populations?) approaches.

Can we describe Grant & Grant (2009) pretty clearly in terms of either or BOTH of these?

What questions arise as we try to separate these two approaches?

How are organisms actually found in nature?

The authors took some time to separate out different ways in which habitat/resource needs might be distributed relative to populations we are evaluating for RI.

Why do the authors argue that this makes a difference for what we expect in movement of genomic diversity from one range to the other?

For discussion

How do we balance the utility of a concept (“species exist and we need to have a way to define them”) and the precision of how that is defined?

Where is mathematical theory and specific language clarifying for our understanding of the species biodiversity that is slow to be defined?

https://www.reuters.com/business/environment/huge-chunk-plants-animals-us-risk-extinction-report-2023-02-06/

For next week a far shorter read!

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As with every week, you can answer: "Given my background and what we have just discussed, what does iT mean to be a species?" And please use a 2nd page for refs