Resisting annihilation: relationships between functional trait dissimilarity, assemblage competitive power and allelopathy

Abstract Allelopathic species can alter biodiversity. Using simulated assemblages that are characterised by neutrality, lumpy coexistence and intransitivity, we explore relationships between within-assemblage competitive dissimilarities and resistance to allelopathic species. An emergent behaviour from our models is that assemblages are more resistant to allelopathy when members strongly compete exploitatively (high competitive power). We found that neutral assemblages were the most vulnerable to allelopathic species, followed by lumpy and then by intransitive assemblages. We find support for our modeling in real-world time-series data from eight lakes of varied morphometry and trophic state. Our analysis of this data shows that a lake's history of allelopathic phytoplankton species biovolume density and dominance is related to the number of species clusters occurring in the plankton assemblages of those lakes, an emergent trend similar to that of our modeling. We suggest that an assemblage's competitive power determines its allelopathy resistance

Domestication Syndrome in Caimito (Chrysophyllum cainito L.): Fruit and Seed Characteristics

Domestication Syndrome in Caimito (Chrysophyllum cainitoL.): Fruit and Seed Characteristics: The process of domestication is understudied and poorly known for many tropical fruit tree crops. The star apple or caimito tree (Chrysophyllum cainito L., Sapotaceae) is cultivated throughout the New World tropics for its edible fruits. We studied this species in central Panama, where it grows wild in tropical moist forests and is also commonly cultivated in backyard gardens. Using fruits collected over two harvest seasons, we tested the hypothesis that cultivated individuals of C. cainito show distinctive fruit and seed characteristics associated with domestication relative to wild types. We found that cultivated fruits were significantly and substantially larger and allocated more to pulp and less to exocarp than wild fruits. The pulp of cultivated fruits was less acidic; also, the pulp had lower concentrations of phenolics and higher concentrations of sugar. The seeds were larger and more numerous and were less defended with phenolics in cultivated than in wild fruits. Discriminant Analysis showed that, among the many significant differences, fruit size and sugar concentration drove the great majority of the variance distinguishing wild from cultivated classes. Variance of pulp phenolics among individuals was significantly higher among wild trees than among cultivated trees, while variance of fruit mass and seed number was significantly higher among cultivated trees. Most traits showed strong correlations between years. Overall, we found a clear signature of a domestication syndrome in the fruits of cultivated caimito in Panama

Complete Mitochondrial Genomes Reveal Neolithic Expansion into Europe

The Neolithic transition from hunting and gathering to farming and cattle breeding marks one of the most drastic cultural changes in European prehistory. Short stretches of ancient mitochondrial DNA (mtDNA) from skeletons of pre-Neolithic hunter-gatherers as well as early Neolithic farmers support the demic diffusion model where a migration of early farmers from the Near East and a replacement of pre-Neolithic hunter-gatherers are largely responsible for cultural innovation and changes in subsistence strategies during the Neolithic revolution in Europe. In order to test if a signal of population expansion is still present in modern European mitochondrial DNA, we analyzed a comprehensive dataset of 1,151 complete mtDNAs from present-day Europeans. Relying upon ancient DNA data from previous investigations, we identified mtDNA haplogroups that are typical for early farmers and hunter-gatherers, namely H and U respectively. Bayesian skyline coalescence estimates were then used on subsets of complete mtDNAs from modern populations to look for signals of past population expansions. Our analyses revealed a population expansion between 15,000 and 10,000 years before present (YBP) in mtDNAs typical for hunters and gatherers, with a decline between 10,000 and 5,000 YBP. These corresponded to an analogous population increase approximately 9,000 YBP for mtDNAs typical of early farmers. The observed changes over time suggest that the spread of agriculture in Europe involved the expansion of farming populations into Europe followed by the eventual assimilation of resident hunter-gatherers. Our data show that contemporary mtDNA datasets can be used to study ancient population history if only limited ancient genetic data is available

The emergence and evolution of Neolithic cattle farming in southeastern Europe:New zooarchaeological and stable isotope data from Džuljunica-Smărdeš, in northeastern Bulgaria (ca. 6200–5500 cal. BCE)

Cattle were of great importance for the Neolithic farmers of southeastern Europe, in particular as farming expanded towards the well-watered regions of Džuljunica (ca. 6200–5500 cal. BCE), one of the earliest known Neolithic settlements in northeastern Bulgaria. The clear stratigraphy and the substantial Bos assemblage from Džuljunica Provided us with a great opportunity to investigate the beginning and evolution of cattle husbandry in the northern Balkans through stable isotope and zooarchaeological analyses. The relative abundance of Bos at Džuljunica leaves no doubt about the importance of beef and cattle herding. Mortality profiles suggest a transition in the early phases of the Neolithic from beef-oriented to mixed beef and milk production husbandry, enabled through intensified post-lactation culling. Stable carbon and oxygen isotope analysis of tooth enamel on a limited number of samples provides no evidence for an extended calving season for increasing milk availability or for vertical mobility. Stable carbon and nitrogen isotope values of bone collagen suggest that cattle were kept near the site, where C3 and C4 plants were available in summer, and that they were occasionally foddered with forest resources in the winter. Cattle experience a diachronic reduction in size on a regional scale, possibly due to farmers' choices aimed at more manageable herds consisting of smaller individuals. Restricting intermixing with local aurochs and the arrival of a new type of cattle may also have contributed to this change. Local factors or inter-regional influences may have influenced the ways cattle husbandry evolved at Džuljunica in particular and in northeastern Bulgaria more generally. More data from the region are necessary to flesh out the role of the interplay among environmental factors, local developments, and inter-regional contacts that facilitate the transfer of skills and traditions relating to the changing modes of cattle husbandry

Data from: Resisting annihilation: relationships between functional trait dissimilarity, assemblage competitive power and allelopathy

Allelopathic species can alter biodiversity. Using simulated assemblages that are characterised by neutrality, lumpy coexistence and intransitivity, we explore relationships between within-assemblage competitive dissimilarities and resistance to allelopathic species. An emergent behaviour from our models is that assemblages are more resistant to allelopathy when members strongly compete exploitatively (high competitive power). We found that neutral assemblages were the most vulnerable to allelopathic species, followed by lumpy and then by intransitive assemblages. We find support for our modeling in real-world time-series data from eight lakes of varied morphometry and trophic state. Our analysis of this data shows that a lake’s history of allelopathic phytoplankton species biovolume density and dominance is related to the number of species clusters occurring in the plankton assemblages of those lakes, an emergent trend similar to that of our modeling. We suggest that an assemblage’s competitive power determines its allelopathy resistanc

Assemblage_HAB_resistance

This is the master program (Matlab) that is used to determine an assemblages sensitivity to allelopath