Elephants versus butterflies: the ecological role of large herbivores in the evolutionary history of two tropical worlds Journal of Biogeography 30(9):1357–1380
Cris Cristoffer1* and Carlos A. Peres2 1CES/CEVN, Luke Air Force Base, AZ, USA, 2Centre for Ecology, Evolution & Conservation, University of East Anglia, Norwich, UK
本文分析已發表的資訊與個人通訊，試圖探討新熱帶與舊熱帶區兩者的草食性動物相存在明顯差異的原因。與新熱帶區相比，舊熱帶區擁有較多生物量的大型草食性動物，原因與具有較低多樣性的小型草食性動物、不同的原住民狩獵方式、較大的樹棲性脊椎動物、較大的果實、花與果的時空分布情形或其他因素有關。本文結果並不支持新熱帶區雨林在前全新世曾經存在過種類豐富的大型草食動物之說法。作者也不認為兩個熱帶區的動物相差異導因於在新世界區人類活動造成的動物滅絕。
Abstract
Aim
Large herbivores have important effects upon Paleotropical ecosystems, but attain much lower biomass densities in the Neotropics. We assess how this difference in herbivore activity has generated different ecological and evolutionary trajectories in the New and Old World tropics. We also propose an explanation for how the greater biomass density in the Old World came about.
Location
Data were compiled primarily from moist tropical forests, although more of the relevant information to address most of our hypotheses was available from the mainland areas of Africa, Asia, and South America than elsewhere.
Methods
We gleaned data from published information and personal communication. We compared body masses and a variety of other types of information for the New- and Old-World tropics. We proposed that interhemispheric differences exist in a variety of processes, including herbivory, frugivory, and flower visitation. We erected hypotheses and evaluated them qualitatively, and, when information was available, tested them using simple ratios of species in various taxonomic and trophic categories. To make the comparisons more meaningful, we specified appropriate data selection criteria.
Results
A general pattern of differences emerges from this review. Compared with Neotropical forests, the much greater biomass densities of large herbivores in Paleotropical forests are associated with a lesser diversity of small herbivores, different hunting methods used by indigenous humans, larger arboreal vertebrates, larger fruits, different patterns of fruit and flower dispersion in space and time, a lesser abundance of most types of reproductive plant parts, and other features. The existence of a species-rich fauna of large herbivores in the pre-Holocene Neotropical rain forest was not supported.
Main conclusions
The potential for large herbivores to cause functional differences between the New and Old World tropical forests has been virtually unexplored, despite the well-known importance of large herbivores in the Old World tropics. The evaluations of our hypotheses suggest that the abundance of large herbivores in the Old World tropics has launched it onto a different evolutionary trajectory than that of the NewWorld tropics. The relevant evidence, although scanty, suggests that the interhemispheric ecological differences are not an artefact of recent megafaunal extinctions in the New World. Recent human activities have, however, reduced population sizes of large wild herbivores in the Old World, and increased population sizes of livestock. This has likely created a rather homogeneous, anthropogenic selection pressure that tends to erase the evolutionary differences between the two tropical worlds.
本文分析已發表的資訊與個人通訊，試圖探討新熱帶與舊熱帶區兩者的草食性動物相存在明顯差異的原因。與新熱帶區相比，舊熱帶區擁有較多生物量的大型草食性動物，原因與具有較低多樣性的小型草食性動物、不同的原住民狩獵方式、較大的樹棲性脊椎動物、較大的果實、花與果的時空分布情形或其他因素有關。本文結果並不支持新熱帶區雨林在前全新世曾經存在過種類豐富的大型草食動物之說法。作者也不認為兩個熱帶區的動物相差異導因於在新世界區人類活動造成的動物滅絕。
Abstract
Aim
Large herbivores have important effects upon Paleotropical ecosystems, but attain much lower biomass densities in the Neotropics. We assess how this difference in herbivore activity has generated different ecological and evolutionary trajectories in the New and Old World tropics. We also propose an explanation for how the greater biomass density in the Old World came about.
Location
Data were compiled primarily from moist tropical forests, although more of the relevant information to address most of our hypotheses was available from the mainland areas of Africa, Asia, and South America than elsewhere.
Methods
We gleaned data from published information and personal communication. We compared body masses and a variety of other types of information for the New- and Old-World tropics. We proposed that interhemispheric differences exist in a variety of processes, including herbivory, frugivory, and flower visitation. We erected hypotheses and evaluated them qualitatively, and, when information was available, tested them using simple ratios of species in various taxonomic and trophic categories. To make the comparisons more meaningful, we specified appropriate data selection criteria.
Results
A general pattern of differences emerges from this review. Compared with Neotropical forests, the much greater biomass densities of large herbivores in Paleotropical forests are associated with a lesser diversity of small herbivores, different hunting methods used by indigenous humans, larger arboreal vertebrates, larger fruits, different patterns of fruit and flower dispersion in space and time, a lesser abundance of most types of reproductive plant parts, and other features. The existence of a species-rich fauna of large herbivores in the pre-Holocene Neotropical rain forest was not supported.
Main conclusions
The potential for large herbivores to cause functional differences between the New and Old World tropical forests has been virtually unexplored, despite the well-known importance of large herbivores in the Old World tropics. The evaluations of our hypotheses suggest that the abundance of large herbivores in the Old World tropics has launched it onto a different evolutionary trajectory than that of the NewWorld tropics. The relevant evidence, although scanty, suggests that the interhemispheric ecological differences are not an artefact of recent megafaunal extinctions in the New World. Recent human activities have, however, reduced population sizes of large wild herbivores in the Old World, and increased population sizes of livestock. This has likely created a rather homogeneous, anthropogenic selection pressure that tends to erase the evolutionary differences between the two tropical worlds.
沒有留言:
張貼留言