Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land

Abstract

Tetrapod biodiversity today is great; over the past 400 Myr since vertebrates moved onto land, global tetrapod diversity has risen exponentially, punctuated by losses during major extinctions. There are links between the total global diversity of tetrapods and the diversity of their ecological roles, yet no one fully understands the interplay of these two aspects of biodiversity and a numerical analysis of this relationship has not so far been undertaken. Here we show that the global taxonomic and ecological diversity of tetrapods are closely linked. Throughout geological time, patterns of global diversity of tetrapod families show 97 per cent correlation with ecological modes. Global taxonomic and ecological diversity of this group correlates closely with the dominant classes of tetrapods (amphibians in the Palaeozoic, reptiles in the Mesozoic, birds and mammals in the Cenozoic). These groups have driven ecological diversity by expansion and contraction of occupied ecospace, rather than by direct competition within existing ecospace and each group has used ecospace at a greater rate than their predecessors.

The origins of modern biodiversity on land

“…As for ecospace use and specialization, Sahney et al (2010) found that global diversity of tetrapod families rose in line with ecospace use, and that these patterns closely match the dominant classes of tetrapods (amphibians in the Palaeozoic, reptiles in the Mesozoic and birds and mammals in the Cenozoic; figure 2). These groups have driven ecological diversity by expansion and contraction of occupied ecospace rather than by direct competition within existing ecospace and each group has used ecospace at a greater rate than their predecessors.…”

“…The closest correlations throughout were between global familial diversity and number of ecospace divisions occupied (Spearman's r ¼ 0.97), much higher than had been expected. Thus, tetrapod families may have become more specialized by dividing diets or habitats, but most of their global expansion was mediated by occupation of new ecospace (Sahney et al 2010). This is not a simple consequence of few families per mode, where addition of a new family would demand a new mode-with 1034 families in 75 modes, the mean occupancy is 13.8 families per mode.…”

“…Xenarthra, Afrotheria and Laurasiatheria). Yet there is little evidence that the break-up of continents through the past 200 Myr has had a major effect on global tetrapod familial biodiversity (Benton 1985b;Sahney et al 2010): major increases in continental numbers in the Jurassic and Cretaceous (figure 1) are not marked by major jumps in diversity, and the slight decline in continental numbers through the past 100 Myr has corresponded to the most dramatic diversity increase. This might seem contrary, and yet alternative continental arrangements in the past, including Pangaea, exhibited regional-scale endemism: there were mountain chains and other barriers to dispersal, as well as major climate and habitat belts (e.g.…”

The Evolution of Contractual and Relational Governance in IS Outsourcing

“…According to the Theory of Biological Interaction, incremental change [37] of species is driven by biological interactions of organisms between and within species [38]. Accordingly, we suggest that incremental change of contractual and relational governance (contract, formal control, trust, informal control) is driven by interactions between and within contractual and relational governance.…”

“…), incremental changes are not exclusively driven by small scale contextual changes. Instead biological interactions are also a major driver of incremental change [37].…”