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Measuring populations, methods, Importance of sampling and reporting, the…
Measuring populations
collected data
Population size – count the number of individuals
Population density – individuals within an area
Historical population change
Demography – sex and age
Temporal changes
Spatial changes
characteristics
distinct individuals
nonmotile indiv
small geographic range
large indiv
small pop size
freindly environment
challenges of volunteers and community scientists
rely on sporadic data collection
temporal and spatial bias
skills of scientists can vary
more likely to observe charasmatic species
long term studies
time consuming
unreliable funding
needs to be easy to follow or tagged species
working in remote and challenging habitats
WWF / ZSL Living planet index (LPI)
WWF (2020) Living Planet Report 2020 - Bending the curve of biodiversity loss
Tracks 21,000 populations
Tracks 4,000 species of fish, amphibians,
reptiles, birds, and mammals
Unitary versus modular organisms
grove of aspen trees
fruiting bodies of mushroom
(Begon et al., 2009)
"Most animals are unitary organisms. Development from the zygote (the fertilized egg) through to the adult involves an irreversible process of growth and tissue differentiation leading to organ development according to a highly regulated schedule."
"Conversely, most plants are modular. Growth and differentiation are normally initiated in 'meristems' at the apices of shoots and roots"
"Modular organisms increase in size by a programme of growth and development that is structurally and functionally repetitive; unitary organisms by contrast do not."
"Each increment in growth can be measured by the number ofmodules produced in a period of time."
IUCN: 56% species are data
deficient
Borgelt et al. (2022)
Communications Biology
methods
mark-recapture
not suitable for every species
indiv personality can shape likelihood of capture
ethics around tagging
spatial distribution or pop changes between sample 1 and 2
quadrats and transects
remote sensing(cametra traps)
remote sensing (passive acoustic monitoring)
Importance of sampling and reporting
the 'ideal' species
