Please help with this plant ecology assignment and you will receive full points
ID: 52371 • Letter: P
Question
Please help with this plant ecology assignment and you will receive full points and a positive comment! Thank you!
The attached article uses molecular techniques to describe new “cryptic” species from two SE Asian frogs long thought to be two species, based on morphology. All of those species were identified by morphology (mostly flower and fruit structure). Parallel studies have not been attempted for tropical trees.
1.) If cryptic speciation commonly occurred in trees, how would it affect understanding of biodiversity?
2.) Can you think of reasons why cryptic speciation might be more or less common in trees?
Please include examples from this article link: http://rsbl.royalsocietypublishing.org/content/2/3/470
Explanation / Answer
Answer:
1)
Molecular phylogeography can lead to a better understanding of the interaction between past climate events, large-scale vegetation shifts, and the evolutionary history of Neotropical seasonal forests. The endangered timber tree species Cedrela fissilis is associated with seasonal forests and occurs throughout South America. We sampled C. fissilis from 56 sites across the species’ range in Brazil and Bolivia and obtained sequence data for nuclear and chloroplast DNA. Most specimens (149 out of 169) exhibited intraindividual polymorphism for the nuclear internal transcribed spacer (ITS). Cloning and an array of complementary sequence analyses indicated that the multiple copies of ITS were functional paralogs – concerted evolution in C. fissilis appeared to be incomplete. Independent Bayesian analyses using either ITS or cpDNA data revealed two separate phylogenetic lineages within C. fissilis that corresponded to populations located in separate geographic regions. The divergence occurred in the Early Pliocene and Late Miocene. We argue that climate-mediated events triggered dispersal events and split ancestral populations into at least two large refugial areas of seasonal forest that were located to the east and west of the present day Cerrado. Upon recent climate amelioration, formerly isolated lineages reconnected and intraspecific hybridization gave rise to intraindividual polymorphism and incomplete concerted evolution in C. fissilis.
link to this article: http://www.sciencedirect.com/science/article/pii/S105579031100385X
2)
The taxonomic challenge posed by cryptic species (two or more distinct species classified as a single species) has been recognized for nearly 300 years, but the advent of relatively inexpensive and rapid DNA sequencing has given biologists a new tool for detecting and differentiating morphologically similar species. Here, we synthesize the literature on cryptic and sibling species and discuss trends in their discovery. However, a lack of systematic studies leaves many questions open, such as whether cryptic species are more common in particular habitats, latitudes or taxonomic groups. The discovery of cryptic species is likely to be non-random with regard to taxon and biome and, hence, could have profound implications for evolutionary theory, biogeography and conservation planning.
Cryptic species: the biodiversity wildcard Increasing worldwide destruction and disturbance of natural ecosystems are precipitating catastrophic extinctions of species . Given that most species remain undescribed, efforts to catalogue and explain biodiversity need to be prioritized. Research on cryptic species has increased exponentially over the past two decades , fuelled in large part by the increasing availability of DNA sequences. Identifying cryptic species challenged biologists and naturalists even before the Linnaean classi- fication system was adopted. Most species descriptions conform with what can be regarded as the morphological or typological species concept, because they predate Mayr’s classic Animal Species and Evolution , which articulated the first incarnation of his ‘biological species concept’ now adopted by many biologists. Because speciation is not always accompanied by morphological change, the true number of biological species is likely to be greater than the current tally of nominal species, most of which are delineated on purely morphological grounds.
Link : http://www.dbs.nus.edu.sg/lab/evol-ecol/documents/Bickford_etal_TREE_2007.pdf
Tropical rainforest and marine habitats might be breeding grounds of cryptic speciation because they are the most species-rich habitats on Earth and because many of those organisms are involved in specialized interspecific interactions. Most publications on cryptic and sibling species concern organisms from temperate regions, and many workers in the tropics feel that tropical ecosystems have many undescribed cryptic species.