Negative relationships between species richness and evenness render common diversity indices inadequate for assessing long-term trends in butterfly diversity

Reports of global declines in animal populations are now numerous and also include snakes, a group of animals now widely regarded as bio indicators. A prerequisite for any conservation management plan to protect or restore snake populations requires a data base that provides insight into population composition and changes. However, snakes are well known to be particularly difficult to quantitatively sample due to their secretive and elusive nature, and hence accumulating an adequate database for analysis requires long-term field studies that involve intensive searches. Populations of four snake species, Zamensis longissimus, Natrix helvetica, Vipera aspis and Hierophis viridiflavus living in two suburban areas of Rome with different extents of habitat alteration (deforestation), Vejo, a less altered site, and Tor Bella Monaca, a high altered site, have been monitored, but with interruptions since 1995. The results indicated that H. viridiflavus was the commonest species at both sites. Male bias was found in all four species but especially in Z. longissimus and V. aspis with detection of juveniles greatest in H. viridiflavus and N. helvetica. Snout to vent lengths (SVL) of H. viridiflavus and Z. longissimus, which were present at both sites, were greater at the less degraded habitat of the two study localities. Community metrics indicated that the degraded habitat had lower species richness, evenness, Shannon and Simpson diversity indices, but a higher dominance index. Recapture frequencies of snakes recaptured either once or multiple times were in general greater at Vejo. The highest population densities were found in H. viridiflavus, followed by V. aspis and N. helvetica, which were similar. However, long term trends in densities show declines in V. aspis and N. helvetica between 1995 and 2019. Population densities were in good agreement with density estimates found in previous studies of snakes in more natural habitats.

Download Full-text

Ecological specialization matters: long-term trends in butterfly species richness and assemblage composition depend on multiple functional traits

Diversity and Distributions ◽

10.1111/ddi.12340 ◽

2015 ◽

Vol 21 (7) ◽

pp. 792-802 ◽

Cited By ~ 51

Author(s):

Anne Eskildsen ◽

Luísa G. Carvalheiro ◽

W. Daniel Kissling ◽

Jacobus C. Biesmeijer ◽

Oliver Schweiger ◽

...

Keyword(s):

Species Richness ◽

Functional Traits ◽

Butterfly Species ◽

Ecological Specialization ◽

Assemblage Composition ◽

Long Term Trends

Download Full-text

Long-Term Trends in Prehistoric Fishing and Hunting on Tobago, West Indies

Latin American Antiquity ◽

10.2307/25063055 ◽

2006 ◽

Vol 17 (3) ◽

pp. 316-334 ◽

Cited By ~ 18

Author(s):

David W. Steadman ◽

Sharyn Jones

Keyword(s):

Species Richness ◽

Relative Abundance ◽

West Indies ◽

Sea Turtles ◽

Food Preferences ◽

Reef Fishes ◽

Archaeological Sites ◽

Long Term Trends ◽

The Difference

AbstractWe compare the bone assemblages of Milford 1 (TOB-3) and Golden Grove (TOB-13) in Tobago, West Indies. Milford 1 is a small preceramic occupation (ca. 3000-2800 cal B.P.), whereas Golden Grove is a large ceramic-period village (ca. 1700-900 cal B.P.). Species richness at TOB-13 is greater than at TOB-3, both in marine (67 vs. 39 fishes) and terrestrial (32 vs. 9) taxa. Major shifts in marine exploitation from the preceramic to ceramic periods can be seen in relative abundance of tuna, toadfishes, and in fishes inhabiting mangrove and brackish water environments, and decreases in relative abundance of parrotfish, carnivorous reef fishes, and sea turtles. The abundance of tuna bones at TOB-13 is uniquely high among West Indian archaeological sites. For terrestrial taxa, the difference in species richness exceeds the expected, including decreased specialization on big game (peccaries) at TOB-13, with a greater tendency to hunt reptiles, birds, and mammals of all sizes at TOB-3. Factors underlying the shifts in fishing and hunting may include different collection methods and food preferences of non-Arawakan (preceramic) vs. Arawakan (ceramic) peoples, as well as human-induced declines in populations of peccaries, sea turtles, and selected fish species. Another possible factor is site setting, with the inhabitants of TOB-13 having enhanced access to mangrove habitats.

Download Full-text

Effects of fire frequency on savanna butterfly diversity and composition: A preliminary study

Koedoe ◽

10.4102/koedoe.v62i1.1617 ◽

2020 ◽

Vol 62 (1) ◽

Cited By ~ 1

Author(s):

Elie Gaget ◽

Catherine L. Parr ◽

Clélia Sirami

Keyword(s):

Species Richness ◽

Low Frequency ◽

Fire Regimes ◽

Spatial Diversity ◽

Fire Frequency ◽

Management Tool ◽

Butterfly Diversity ◽

Fire Experiment ◽

In Fire

Fire plays a major role in many biomes, is widely used as a management tool and is likely to be affected by climate change. For effective conservation management, it is essential to understand how fire regimes affect different taxa, yet responses of invertebrates are particularly poorly documented. We tested how different fire frequencies influence savanna butterfly diversity and composition by using a long-term savanna fire experiment initiated in 1954 in the Kruger National Park (South Africa). We compared butterfly abundance, species richness and community composition across three fire frequencies: high (burnt annually), medium (burnt triennially) and low (burnt twice in 60 years). Plots with high fire frequency hosted higher abundance than medium- or low-frequency plots. Fire frequencies did not affect species richness, but they led to distinct communities of butterflies. Our findings suggest that, in view of the three fire frequencies tested, a spatial diversity of fire frequencies may increase butterfly diversity at the landscape level in wet savannas. Managers may need to promote a greater diversity of fire frequencies by increasing fire frequency in some areas to provide habitat for species requiring high fire frequency, and by decreasing fire frequency in a large proportion of the landscape to provide fire refuges. This study provides new insights for butterfly conservation in savannas and highlights several knowledge gaps, which further studies should address for insect responses to be given adequate consideration in fire management strategies.Conservation implications: A spatial diversity of fire frequencies may increase butterfly diversity. Managers may need to promote a greater diversity of fire frequencies by increasing fire frequency in some areas to provide habitat for species requiring high fire frequency, and by decreasing fire frequency in other areas to provide fire refuges.

Download Full-text

Long-term trends in helminth infections of wood mice (Apodemus sylvaticus) from the vicinity of Malham Tarn in North Yorkshire, England

Parasitology ◽

10.1017/s0031182020002243 ◽

2020 ◽

pp. 1-13

Author(s):

Jerzy M. Behnke ◽

Michael T. Rogan ◽

Philip S. Craig ◽

Joseph A. Jackson ◽

Geoff Hide

Keyword(s):

Species Richness ◽

Wood Mouse ◽

Heligmosomoides Polygyrus ◽

Mouse Population ◽

Wood Mice ◽

Higher Taxa ◽

Helminth Infections ◽

Underlying Causes ◽

Long Term Trends

Abstract Helminth infections in wood mice (n = 483), trapped over a period of 26 years in the woods surrounding Malham Tarn in North Yorkshire, were analysed. Although 10 species of helminths were identified, the overall mean species richness was 1.01 species/mouse indicating that the helminth community was relatively depauperate in this wood mouse population. The dominant species was Heligmosomoides polygyrus, the prevalence (64.6%) and abundance (10.4 worms/mouse) of which declined significantly over the study period. Because of the dominance of this species, analyses of higher taxa (combined helminths and combined nematodes) also revealed significantly declining values for prevalence, although not abundance. Helminth species richness (HSR) and Brillouin's index of diversity (BID) did not show covariance with year, neither did those remaining species whose overall prevalence exceeded 5% (Syphacia stroma, Aonchotheca murissylvatici and Plagiorchis muris). Significant age effects were detected for the prevalence and abundance of all higher taxa, H. polygyrus and P. muris, and for HSR and BID, reflecting the accumulation of helminths with increasing host age. Only two cases of sex bias were found; male bias in abundance of P. muris and combined Digenea. We discuss the significance of these results and hypothesize about the underlying causes.

Download Full-text