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Evolutionary approaches to marine conservation
Transcript of Evolutionary approaches to marine conservation
= 1 + 1 + 5 + 1 = 8 Random distribution of risk does not reduce evolutionary diversity substantially Huang (2012, PLoS ONE) Evolutionarily Distinct & Globally Endangered (EDGE) corals ED x GE
= EDGE ED = 0.5 + 0.2 + 0.33 + 1 = 2.03 ED = 0.5 + 5 = 5.5 ED = 2.5 + 1 + 2 = 5.5 Based on EDGE (Isaac et al. 2007, PLoS ONE) Using evolutionary distinctiveness (ED) of species to aid conservation prioritization Huang (2012, PLoS ONE) 1293 Scleractinia spp.
837 reef corals (complete)
456 non-reef corals (64%)
Based on molecular, morphological & taxonomic data Least Concern (GE ~0.1%) Near Threatened (GE ~1%) Vulnerable (GE ~10%) Endangered (GE ~67%) Critically Endangered (GE ~99%) Evolutionary Approaches
to Marine Conservation Danwei Huang
3 December 2012 How many species are there on Earth? How many species are in the ocean? 15-25% of species live in the ocean
Of 33 animal phyla
32 phyla live in the ocean
12 phyla live on land
73 animal classes in the sea
35 animal classes in freshwater
33 animal classes on land Mora et al. (2011, PLoS Biol.) Mora et al. (2011, PLoS Biol.) Estimates of marine species richness Appeltans et al. (2012, Curr. Biol.) McCarthy et al. (2012, Science) $70 billion annually needed to preserve all birds globally
Currently, only ~10% funded Barnosky et al. (2011, Nature) Limited resources impose practical limitations on conservation.
Therefore, we need to prioritize species for conservation. Threat Functional value Historical value Marine ecosystems are declining Under current rates of extinction for vertebrates, it would take ~240 to 2270 years to reach magnitude of species loss equivalent to Big Five. On what bases can we prioritize species for conservation? Cadotte et al. (2011, J. Appl. Ecol.) Most communities show ecological redundance
(i.e. different species fill similar ecological niches and contribute to similar ecosystem function) Cayman Islands fish food web Priority:
Species performing unique ecosystem functions
(e.g. the few top predators on reefs) Eretmochelys imbricata Hawksbill turtle Lepidochelys olivacea Olive ridley turtle "Quite apart from many theoretical and practical problems that continue to affect the species concept and its application, is it appropriate for conservation purposes to regard all species as equal in this manner? To a conservationist, regardless of relative abundance, is Welwitschia equal to a species of Taraxacum? Is the panda equivalent to one species of rat?" Within species, we can also identify populations that tend to contribute more to future diversity.
This requires recognition of (1) populations that are genetically distinct, and (2) source-sink relationships. time "source" "sink" Carpenter et al. (2011, J. Mar. Bio.) Haplotype: a set of alleles (DNA sequences) at adjacent locations (loci) on the chromosome that are transmitted together.
A haplotype may be one locus, several loci, or an entire chromosome depending on the number of recombination events that have occurred between a given set of loci. Onexposure /1x.com © Alex Cearns Tridacna maxima Results
- 4 very distinct groups of populations
(1) Indonesian throughflow & Sulawesi
(2) Eastern Indian Ocean & Java Sea
(3) Western Pacific
(4) Red Sea
- High connectivity within groups due to seasonal currents (dotted lines)
- Ancestral sequence likely #1; upstream of dominant currents (solid lines) - Geographically widespread
- Hermaphroditic clams
- Release sperm, eggs into water column
- Fertilized eggs and free-swimming larvae transported along currents
- Up to 10 days in water column (short) Nuryanto & Kochzius (2009, Coral Reefs) Rugose giant clam Method
- Sample 14 populations across Indo-Pacific
- Collect mantle tissue from clams
- Extract DNA
- Sequence cytochrome c oxidase I (COI) gene
- Generate genetic network Carpenter et al. (2011, J. Mar. Bio.) Distinctiveness & risk of each species
Distribution of risks on the tree of life ED = length of species' terminal branch plus species-weighted shares of ancestral branches Prerequisites for assessment
1. Majority of species assessed by IUCN for threat status
2. Complete sampling of evolutionary tree (species and branch lengths) 1. Majority of species assessed by IUCN for threat status 2. Complete sampling of evolutionary tree (species and branch lengths) Crown-of-thorns seastar Bleaching (loss of algal symbiont) Least Concern Near Threatened Vulnerable Endangered Critically Endangered Disease GE = probability of extinction in the next 100 years All threatened
3 Critically Endangered
Highly distinct species
(e.g. genera with single species)
Main Caribbean reef builders with high functional value
Species from all major reef regions Veron et al. (2011) Total length of at-risk branches
= (1 + 2 + 1 + 1) + 1 + 3 + 10 = 19 Clustering of risk on the tree of life can lead to large declines in evolutionary diversity Corals susceptible to individual threats are closely related.
Threatened species are not clustered on coral tree of life. Clustering of risk on the coral tree of life can lead to large declines in evolutionary diversity Limited resources force us to prioritize species (and regions) for conservation.
3 general approaches of assessment: threat, functional and historical.
Within species, based on genetic connectivity, we can identify populations that contribute more to future diversity: (1) populations that are genetically distinct, and (2) source-sink relationships.
Among species, based on the shape and distribution of branch lengths on the evolutionary tree, we can assess (1) the historical value of each species in combination with threat status, and (2) clustering of threats on the tree. Notes
1. Focus on marine conservation: world's marine biodiversity and ecosystems under threat from habitat loss, pollution, climate change; important to learn various ways in which we can conserve species; introduce the concepts of evolution / biological history to aid in conservation prioritization; although biologists have thought about this for a long time, only recently applied on living organisms for conservation, so no textbook chapter; can get technical, goal not to teach how to collect and analyze data for evolution and conservation, but rather to learn how to interpret results / papers to better understand how to preserve biodiversity in general
2. All of us, and organisms belong to tree of life, having evolved from common ancestor >3 billion years ago; diversified resulting in diversity today at the edge of circle; via branching events: every node is a split of 1 sp. into 2 also known as speciation, but also extinction (99% of species ever lived extinct)
3. Most challenging question in biology
4. Estimate based on accumulation curves of taxa known; species curve globally hasn't plateaued; can use composition of higher taxa to estimate species
5. Recent model showing only about 15% of species catalogued, even less in the oceans
6. Compilation of estimates for marine species; most recent arrowed, based on empirical rates of discovery and expert opinion
7. Despite uncertainty, we know that the marine realm is a very significant system in terms of biodiversity; only up to 25% marine, but terrestrial mainly insects; higher taxa more representative of diversity, not just species diversity
8. Declining reefs, seagrasses, mangroves, deep sea; leading to loss of habitat and species
9. To qualify as mass extinction event: at least 75% of species loss within a short geological time frame (~2 Myr); has there been extinctions in recent times, and do they constitute mass extinction
10. Current extinction is low, but include threatened species (according to the IUCN Red List, discussed later), nearing 75%; high potential mass extinction event if we don't do anything to avert disaster
11. Expensive, and getting more costly to conserve species; underfunded
16. Ecological redundance, e.g. predator with many different prey, so removing a single prey species not decreasing ecosystem function much; to prioritize according to functional value is to preferentially protect species that have unique function(s) with many links to other species that once lost can lead to large losses of function
19. IUCN: International Union for Conservation of Nature publishes Red List of Threatened Species, soliciting expert opinion based on empirical trends and biology for every species, assigning threat status; started publishing lists in late 1990s, now only about 6% of all known species assessed Boundaries can be estimated by looking at population tree, but historical source-sink dynamics can only inferred by haplotype tree or network Tree information: (1) shape; (2) branch lengths Top 3 mammals: monotremes (4 living species) ED www.wikipedia.com www.wikipedia.com http://proopnarine.wordpress.com