- Deep-sea species diversity is shaped by energy availability (i.e. thermal energy and nutrients)
- Continental shelf to upper-slope species richness consistently peaks in tropical Indo-west Pacific and Caribbean (0–30°) latitudes, and is well explained by variations in water temperature.
- Deep-sea species show maximum richness at higher latitudes (30–50°, i.e. polar regions), where they are concentrated in areas with high carbon export flux and regions close to continental margin (richness drops as you get away from the land).
- Global brittle star richness, in terms of species, peaks in the tropics at "shallow" continental shelf depths (20-200 m) and upper slope depths (200-1200 m). These peaks drop when you get below 2000 m depths.
- Data are consistent with a hypothesis that deep-sea species richness is maintained by species migration from shallower regions. i.e., "high energy areas feed low energy areas"
- Historically we have looked at tropical areas as the focus of conservation efforts, but if we TRULY want to conserve deep-sea habitats we will need to consider the areas which show DEPENDENCE on the shallower regions for diversity.
1. Echinoderms, including brittle stars live ONLY in the oceans. No freshwater, or land relatives.
2. Brittle stars are EVERYWHERE. They are one of the most numerically abundant groups of echinoderms known.
The Nature paper is sort of the "other shoe" that has dropped with big discoveries. (Remember that
echinoderms have five shoes!)
Dr. O'Hara's other BIG news in recent years has been the announcement of this: a comprehensive family tree of the ophiuroids!
- How are all the different groups related? (e.g., how are basket stars related to other brittle stars?)
- How did they diversify? Where?
- What kind of habitat did they diversify into?
- Which brittle stars form actual, NATURAL biological groups?
|image from Museum Victoria: http://researchdata.museum.vic.gov.au/brittlestar/www/o_lym.htm|
These efforts are some of the latest results from Tim O'Hara's "Big Data" ophiuroid work!
Remember that the fundamental basis for ALL of these projects has been Tim's skill in TAXONOMY of brittle stars. Many of these species were difficult to identify and reconcile without skills in how to tell them apart. Here was an account of Tim's work at the Museum national d'Historie naturelle in Paris! He identified over 1000 specimens while I was there.
Other past efforts from Tim's lab:
Here's the time he and his student worked on the mystery of cryptic species in the Australian biscuit star Tosia australis!
Here's his research on discovering the distribution of brittlestars in lateral bands