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Causal evidence between monsoon and evolution of rhizomyine rodents.

López-Antoñanzas R, Knoll F, Wan S, Flynn LJ - Sci Rep (2015)

Bottom Line: We showed the existence of three drops in biodiversity during the evolution of rhizomyines, all of which reflected elevated extinction rates.Our results demonstrated linkage of monsoon variations with the evolution and biogeography of rhizomyines.Paradoxically, the evolution of rhizomyines was accelerated during the phases of weakening of the monsoons, not of strengthening, most probably because at those intervals forest habitats declined, which triggered extinction and progressive specialization toward a burrowing existence.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Earth Sciences, University of Bristol, Bristol, United Kingdom [2] Departamento de Paleobiología, Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain.

ABSTRACT
The modern Asian monsoonal systems are currently believed to have originated around the end of the Oligocene following a crucial step of uplift of the Tibetan-Himalayan highlands. Although monsoon possibly drove the evolution of many mammal lineages during the Neogene, no evidence thereof has been provided so far. We examined the evolutionary history of a clade of rodents, the Rhizomyinae, in conjunction with our current knowledge of monsoon fluctuations over time. The macroevolutionary dynamics of rhizomyines were analyzed within a well-constrained phylogenetic framework coupled with biogeographic and evolutionary rate studies. The evolutionary novelties developed by these rodents were surveyed in parallel with the fluctuations of the Indian monsoon so as to evaluate synchroneity and postulate causal relationships. We showed the existence of three drops in biodiversity during the evolution of rhizomyines, all of which reflected elevated extinction rates. Our results demonstrated linkage of monsoon variations with the evolution and biogeography of rhizomyines. Paradoxically, the evolution of rhizomyines was accelerated during the phases of weakening of the monsoons, not of strengthening, most probably because at those intervals forest habitats declined, which triggered extinction and progressive specialization toward a burrowing existence.

No MeSH data available.


Related in: MedlinePlus

Biostratigraphic ranges of mammalian lineages from the Siwalik record (first and last occurrence inferred), late Miocene of the Potwar Plateau, after data from Barry et al.46(A) and Badgley et al.53 (B). Species that went extinct between 10.4 and 9.8 Ma are in red, whereas appearances at that time are in green. The horizontal line in excess of 10 Ma indicates the initiation of the weakening of the monsoon, and coincides with the beginning of radiation of fossorial rhizomyine rodents.
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f3: Biostratigraphic ranges of mammalian lineages from the Siwalik record (first and last occurrence inferred), late Miocene of the Potwar Plateau, after data from Barry et al.46(A) and Badgley et al.53 (B). Species that went extinct between 10.4 and 9.8 Ma are in red, whereas appearances at that time are in green. The horizontal line in excess of 10 Ma indicates the initiation of the weakening of the monsoon, and coincides with the beginning of radiation of fossorial rhizomyine rodents.

Mentions: There are numerous palaeontological studies that support an important climatic change in the Himalayan area since the beginning of the Late Miocene. For instance, after 12 Ma, the δ18O of fossil large mammal tooth enamel records a shift toward a drier environment in Pakistan23. In addition, the exceptional Siwalik fossil record has allowed the identification of a period of high faunal turnover at about 10.3 Ma that is characterized by a high level of disappearance46. In fact, more than 30% of the whole mammal fauna disappeared (11 out of 36 taxa) and 17 new taxa appeared (Fig. 3). Furthermore, the most significant faunal change in bovids occurs not long after 11 Ma47, nearly coinciding with the arrival of hipparionine horses. The rodent fossil record shows important changes such as the decline of cricetids, which had dominated the Siwalik Miocene since 18 Ma, and the local extinction of ctenodactylines48. Furthermore, Kimura et al.49 identified at this time (10.5 to 10.2 Ma) the first significant divergence in molar shape between the two murines Karnimata and Progonomys, which could be linked to environmental changes. Flynn685051 observed an increase in hypsodonty in Late Miocene rhizomyines from the Pakistan Siwaliks. This has been tentatively correlated with a transition to a drier and more seasonal climate beginning around 9.2 Ma, which intensified by 7.8 Ma, as evidenced by changes in the floodplain deposition and vegetation46. The change in rodent fauna evidenced in the area by Flynn & Jacobs52 at about this time also supports an increase in aridity and a change in forest ecology.


Causal evidence between monsoon and evolution of rhizomyine rodents.

López-Antoñanzas R, Knoll F, Wan S, Flynn LJ - Sci Rep (2015)

Biostratigraphic ranges of mammalian lineages from the Siwalik record (first and last occurrence inferred), late Miocene of the Potwar Plateau, after data from Barry et al.46(A) and Badgley et al.53 (B). Species that went extinct between 10.4 and 9.8 Ma are in red, whereas appearances at that time are in green. The horizontal line in excess of 10 Ma indicates the initiation of the weakening of the monsoon, and coincides with the beginning of radiation of fossorial rhizomyine rodents.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4355670&req=5

f3: Biostratigraphic ranges of mammalian lineages from the Siwalik record (first and last occurrence inferred), late Miocene of the Potwar Plateau, after data from Barry et al.46(A) and Badgley et al.53 (B). Species that went extinct between 10.4 and 9.8 Ma are in red, whereas appearances at that time are in green. The horizontal line in excess of 10 Ma indicates the initiation of the weakening of the monsoon, and coincides with the beginning of radiation of fossorial rhizomyine rodents.
Mentions: There are numerous palaeontological studies that support an important climatic change in the Himalayan area since the beginning of the Late Miocene. For instance, after 12 Ma, the δ18O of fossil large mammal tooth enamel records a shift toward a drier environment in Pakistan23. In addition, the exceptional Siwalik fossil record has allowed the identification of a period of high faunal turnover at about 10.3 Ma that is characterized by a high level of disappearance46. In fact, more than 30% of the whole mammal fauna disappeared (11 out of 36 taxa) and 17 new taxa appeared (Fig. 3). Furthermore, the most significant faunal change in bovids occurs not long after 11 Ma47, nearly coinciding with the arrival of hipparionine horses. The rodent fossil record shows important changes such as the decline of cricetids, which had dominated the Siwalik Miocene since 18 Ma, and the local extinction of ctenodactylines48. Furthermore, Kimura et al.49 identified at this time (10.5 to 10.2 Ma) the first significant divergence in molar shape between the two murines Karnimata and Progonomys, which could be linked to environmental changes. Flynn685051 observed an increase in hypsodonty in Late Miocene rhizomyines from the Pakistan Siwaliks. This has been tentatively correlated with a transition to a drier and more seasonal climate beginning around 9.2 Ma, which intensified by 7.8 Ma, as evidenced by changes in the floodplain deposition and vegetation46. The change in rodent fauna evidenced in the area by Flynn & Jacobs52 at about this time also supports an increase in aridity and a change in forest ecology.

Bottom Line: We showed the existence of three drops in biodiversity during the evolution of rhizomyines, all of which reflected elevated extinction rates.Our results demonstrated linkage of monsoon variations with the evolution and biogeography of rhizomyines.Paradoxically, the evolution of rhizomyines was accelerated during the phases of weakening of the monsoons, not of strengthening, most probably because at those intervals forest habitats declined, which triggered extinction and progressive specialization toward a burrowing existence.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Earth Sciences, University of Bristol, Bristol, United Kingdom [2] Departamento de Paleobiología, Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain.

ABSTRACT
The modern Asian monsoonal systems are currently believed to have originated around the end of the Oligocene following a crucial step of uplift of the Tibetan-Himalayan highlands. Although monsoon possibly drove the evolution of many mammal lineages during the Neogene, no evidence thereof has been provided so far. We examined the evolutionary history of a clade of rodents, the Rhizomyinae, in conjunction with our current knowledge of monsoon fluctuations over time. The macroevolutionary dynamics of rhizomyines were analyzed within a well-constrained phylogenetic framework coupled with biogeographic and evolutionary rate studies. The evolutionary novelties developed by these rodents were surveyed in parallel with the fluctuations of the Indian monsoon so as to evaluate synchroneity and postulate causal relationships. We showed the existence of three drops in biodiversity during the evolution of rhizomyines, all of which reflected elevated extinction rates. Our results demonstrated linkage of monsoon variations with the evolution and biogeography of rhizomyines. Paradoxically, the evolution of rhizomyines was accelerated during the phases of weakening of the monsoons, not of strengthening, most probably because at those intervals forest habitats declined, which triggered extinction and progressive specialization toward a burrowing existence.

No MeSH data available.


Related in: MedlinePlus