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#alpha diversity

3 public questions tagged with this topic.

BIODIVERSITY & IDH

Which of the following shows greater alpha diversity?

Alpha diversity is defined within a single local habitat or community. Among the scale descriptions given, “single habitat” is therefore the appropriate unit for an alpha-diversity measurement. An ecosystem may contain several habitat types, multiple communities explicitly span a broader comparison, and a whole region corresponds to gamma diversity. The wording “greater alpha diversity” is imprecise because a spatial category alone does not guarantee a larger numerical value; actual richness and abundance data are needed to decide which specific habitat is most diverse. The scientifically valid point is that alpha is assessed at the single-habitat scale, not that every single habitat has more species than every region. Beta diversity describes change among local habitats, while gamma diversity pools them across the region. A local community may have high alpha diversity because it contains many evenly represented species, yet regional gamma will ordinarily be at least as large in richness terms because it includes the union of local species. The keyed choice should thus be understood as identifying the scale of alpha diversity, with the comparative adjective treated as a flaw in the stem rather than a literal cross-scale ranking.

Ref: NCERT Biology Class 12, Ch. 15 Biodiversity and Conservation

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BIODIVERSITY

Which pair shows highest alpha diversity?

Alpha diversity concerns the species diversity within one local community. A ranking that assigns community A the highest alpha diversity implies that A has the largest within-community richness, the greatest evenness, or the highest value of a specified composite index relative to B, C, and D. The criterion must be kept consistent: richness counts species only, Shannon diversity weights both richness and evenness, and Simpson-based diversity places greater emphasis on common species. Consequently, a community with the longest species list need not rank highest by every index if it is overwhelmingly dominated by one species. Alpha diversity should also not be confused with beta diversity, which compares turnover between communities, or gamma diversity, which describes the pooled regional species set. Ecologically, high alpha diversity can reflect resource heterogeneity, moderate disturbance, productive conditions within limits, or reduced competitive exclusion, but the observed ranking depends on the supplied abundance data. Since the table, graph, or “pair” information referenced by the item is absent from the extracted text, community A cannot be independently recalculated. The keyed result is interpretable only as A having the strongest local diversity statistic in the omitted source material.

Ref: NCERT Biology Class 12, Ch. 15 Biodiversity and Conservation

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BIODIVERSITY

Which region shows maximum α and β diversity respectively?

Alpha diversity describes richness and abundance within a single local community, whereas beta diversity describes compositional change among communities. Thus, identifying the region labelled Q as having maximum alpha diversity requires Q to contain the richest local assemblage, or the assemblage with the greatest combined richness and evenness if an index is supplied. Identifying S as having maximum beta diversity requires the greatest species turnover among its sampled sites: sites in S should share relatively few species and differ strongly in composition. Beta diversity is not simply the total number of species in a region; a region may have high gamma diversity but modest beta diversity if every site contains nearly the same species. Conversely, environmentally heterogeneous regions can have high beta diversity because different habitats filter different species. The pairing Q and S therefore expresses two distinct spatial properties—high diversity within a site and high differentiation between sites. The underlying diagram or species table is needed to recompute these rankings, but the conceptual basis for the keyed pairing is local diversity in Q and maximum turnover in S.

Ref: NCERT Biology Class 12, Ch. 15 Biodiversity and Conservation

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