Ecology of small mammals and their ectoparasites in Mount Meru, Tanzania: insights for biodiversity conservation
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2024-05
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Sokoine University of Agriculture
Abstract
This Thesis has been prepared in accordance with the Publishable
Manuscripts format of the Sokoine University of Agriculture. The
study on the elevational distribution of non-volant small mammals
over time, their demographic characteristics, and their associations
with arthropod ectoparasites was conducted between 2021 and
2022 at different elevations and habitats in Tanzania's second-
highest mountain, Mount Meru. Mount Meru is one of the
biodiversity hotspots in eastern Africa, hosting high level of species
richness and endemism, and providing important ecosystem
services. However, relatively, little is known about the ecology of
small mammals and their arthropod ectoparasites. Similarly, little is
known about the effects of environmental factors on the small
mammal distribution, which potentially extending to the parasites
they host. Tanzania is among the handful of countries in Africa
where active foci of deadly zoonotic diseases that can be
transmitted by small mammals and their ectoparasite vectors have
been persistent. Moreover, Mount Meru is home for endemic and
threatened species that are documented on the IUCN Red List.
However, there is currently no available information regarding the
possible role of arthropod ectoparasites of small mammals in the
transmission of zoonotic disease.
The over all goal of the study was to understand the ecological
dynamics and distribution patterns of small mammals and their
arthropod ectoparasites across different elevations of Mount Meru in
Tanzania. The study aimed at addressing three key specific
objectives: i) Assesing a decade-long change in the elevational
distribution of non-volant small mammals on Mount Meru; ii)
determining the breeding and demographic aspects of montemys
delectorum, an east african endemic rodent in mount Meru;
iii) Examining arthropod ectoparasites of two rodent species occurring
in varied elevations on Tanzania’s second highest mountain. To address the first objective, the small mammals were surveyed
from February to November 2021 at six elevations between 1500 m
and 3650 m using Sherman and Havahart traps. The results show
that two shrew and thirteen rodent species were recorded, including
Crocidura newmarki and Lophuromys verhageni, which are endemic
to the study area. Species richness was highest at mid-altitudes, in
line with the general patterns globally, though less pronounced in
Africa. The species Arvicanthis niloticus, Mastomys natalensis,
Lemniscomys striatus, Dasymys incomtus, and Cricetomys ansorgei
were not documented in 2009 but have been recorded in 2021.
Upward shifts in species’ ranges were observed between 2009 and
2021, suggesting the influence of climate change on the small
mammal community.
It is important to note that the rodent species mentioned in Chapter 2
as Praomys species have been identified as Montemys delectorum
after genetic identification and recent taxonomic revisions.
For the second objective, a Capture – mark – release studies were
undertaken in dense and open patchy forests in four 70 m X 70 m
grids from February 2021 to June 2022. The findings revealed that
the species exhibited bimodal patterns of breeding seasonality,
characterized by a low rate occurring during the short interval
between December and February and a pronounced rate taking
place from May to July. The population of Montemys delectorum
was unstable in the different forest types. There was a larger
population in the patchy open forest (F = 8.1; df = 1; p = 0.0001)
than in dense forest, suggesting its importance as a refuge for the
species.
To achieve the third objective, trapping of the two most dominant
rodent species of the study area, Montemys delectorum and
Rhabdomys dilectus, from five elevations (1500 to 3500 m), were
examined for arthropod ectoparasite infestations. The results
revealed that Ctenophthalmus calceatus cabirus, Dinopsyllus
ellobius, Varroa rindereri, and Xenopsylla cheopis were recovered
from the rodents. This study demonstrates that the elevational
distribution of arthropod ectoparasites is influenced by host sex, host
species, and environmental temperature. With rising altitude,
parasite prevalence and abundance decrease, indicating that colder
environmental conditions at higher altitudes inhibit parasite
reproduction and development. This indicates conservation efforts
should focus on higher altitudes. Moreover, the rodents and
ectoparasites reported in this study have been identified as possible
vectors of medical and veterinary diseases in different parts of
Africa, including Tanzania. It is crucial to take precautions in order to
effectively reduce the risk of parasitic infection, which can pose an
additional threat to both the endemic and threatened species listed
on the IUCN Red List as well as the overall biodiversity of the study
area. Furthermore, molecular results from this study reported a
previously unidentified mite species within the Mesostigmata
taxonomic group that had previously been recognized exclusively as
a parasite of honeybees. Further research efforts may provide
insights into the significance of this particular species of mite, Varroa
rindereri. Generally, while there remains much to be learned, this
particular study establishes the foundation for future initiatives in
wildlife disease surveillance and biodiversity conservation
management.
In abroader sense, the shift in the distribution of small mammals and
their ectoparasites on Mount Meru is a microcosm of the broader
challenges facing mountain ecosystems worldwide. These insights
go beyond the immediate context of Mount Meru and suggest that
we need to consider the long-term consequences of environmental
dynamics on biodiversity conservation. As these complexities
continue to shape mountain landscapes, their impact is not limited to
species interactions but also touches the field of human well-being.
The conservation of biodiversity is intrinsically linked to our own well-
being, as biodiversity and human societies are intricately intertwined.
Therefore, the findings of this research serve as an urgent reminder
for effective conservation action.
Description
PhD Thesis
Keywords
Ecology, Small Mammals, Their Ectoparasites, Mount Meru, Biodiversity Conservation, Tanzania