Maintaining Diversity & Ecosystem Functions Flashcards
what varies between different measures of diversity
scale and point of comparison
what is the spatial scale of alpha diversity
local ecological community, kept within standard area, e.g. 1000 sq. m - 0.1 hectares
give an example of how beta diversity can be calculated
Beta diversity = 1- (alpha diversity/gamma diversity)
issues with estimating species richness in the tropics
“sampling is rarely random and unbiased, so it is hard to use current samples to extrapolate
some of the most hyperdiverse estimates are based on v small sample sizes
synonym issue - species that share names or have been catalogued twice”
species richness reading
Mora et al 2011, they guess 8.7m eukaryotes
what is the predator prey model for theorising species richness in the tropics
there are more taxonomists than ever before, but they’re finding the same number of species, so perhaps there aren’t many more. Estimate 2 million. Costello et al 2011
which approach to calculating species richness in the tropics is used by Scheffers et al 2012
add best estimates of each taxa, excluding very high values (over 20 million). They guess 9.6m
given that the averaging of the 3 methods gives 8 million total species in the tropics, how many of those are known to science
1.6 million or 20%
given that the averaging of the 3 methods gives 8 million total species in the tropics, how many of those are known to science
in the tropics, which factor drives the alpha diversity of trees
moisture availability - negative relationship w length of dry season
in basic terms, what are the 2 types of theories on how the tropics avoid competitive exclusion
either the tropics are better at creating lots of small niches or they have some mechanism to avoid competitive exclusion and allow survivorship of rare species
give an example of niche differentiation with regards to light in tropical forests
light demanding pioneer species grow fast and die in the underbrush, and shade tolerant species grow slower but last longer
what is the intermediate disturbance hypothesis
“open area allows colonization by early successional species, which are slowly outcompeted by slower growing successional species.
Max diversity is in the intermediate stage, when there are bits of forest that allow both”
reading for intermediate disturbance hypothesis
Molino and Sabatier 2001
issues with intermediate disturbance hypothesis
not a significant enough effect on diversity, most species in a forest are not pioneer species
issues with soil type diversity explaining how so many species coexist
hundred of species live on each one of the small soil types, so they still don’t have separate soil niches from each other but can coexist
what is the regeneration niche idea of explaining niche differentiation
plants need different conditions across their life cycle, giving more opportunities for niche separation - Grubb 1977
issues with regeneration niche explaining niche differentiation
difficult to test, so no evidence
what is another name for the Janzen Connell hypothesis
density/distance dependent mortality OR negative density dependence
what is the Janzen Connell hypothesis
most tree seeds get dispersed near the parent tree, which then get predated on more, so the ones that survive are the few that dispersed further
which 2 processes make up the Janzen Connell hypothesis
density responsive mortality and distance responsive mortality
what is density responsive mortality
one of 2 processes making up the Janzen Connell hypothesis which works to stop common species becoming more common by predation occurring more near high density areas
what is distance responsive mortality
one of 2 processes making up the Janzen Connell hypothesis which works to help rare species survive by having predators congregate near high density areas, avoiding further dispersed seeds
reading for density response mortality
bell et al 2006
reading for distance responsive mortality
comita et al 2010
