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1. Temperature controls phenology in continuously flowering Protea species of subtropical Africa

   https://doi.org/10.1002/aps3.1232  

   Daru, Barnabas H. ; Kling, Matthew M. ; Meineke, Emily K. ; van Wyk, Abraham E. ( March 2019 , Applications in Plant Sciences)

   Herbarium specimens are increasingly used as records of plant flowering phenology. However, most herbarium‐based studies on plant phenology focus on taxa from temperate regions. Here, we explore flowering phenologic responses to climate in the subtropical plant genusProtea(Proteaceae), an iconic group of plants that flower year‐round and are endemic to subtropical Africa.

   We present a novel, circular sliding window approach to investigate phenological patterns developed for species with year‐round flowering. We employ our method to evaluate the extent to which site‐to‐site and year‐to‐year variation in temperature and precipitation affect flowering dates using a database of 1727 herbarium records of 25Proteaspecies. We also explore phylogenetic conservatism in flowering phenology.

   We show that herbarium data combined with our sliding window approach successfully captured independently reported flowering phenology patterns (r= 0.93). Both warmer sites and warmer years were associated with earlier flowering of 3–5 days/°C, whereas precipitation variation had no significant effect on flowering phenology. Although species vary widely in phenological responsiveness, responses are phylogenetically conserved, with closely related species tending to shift flowering similarly with increasing temperature.

   Our results point to climate‐responsive phenology for this important plant genus and indicate that the subtropical, aseasonally flowering genusProteahas temperature‐driven flowering responses that are remarkably similar to those of better‐studied northern temperate plant species, suggesting a generality across biomes that has not been described elsewhere.

    

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2. Reproductive losses due to climate change‐induced earlier flowering are not the primary threat to plant population viability in a perennial herb

   https://doi.org/10.1111/1365-2745.13146  

   Iler, Amy M. ; Compagnoni, Aldo ; Inouye, David W. ; Williams, Jennifer L. ; CaraDonna, Paul J. ; Anderson, Aaron ; Miller, Tom E. X. ; Catford, ed., Jane ( March 2019 , Journal of Ecology)

   Despite a global footprint of shifts in flowering phenology in response to climate change, the reproductive consequences of these shifts are poorly understood. Furthermore, it is unknown whether altered flowering times affect plant population viability.

   We examine whether climate change‐induced earlier flowering has consequences for population persistence by incorporating reproductive losses from frost damage (a risk of early flowering) into population models of a subalpine sunflower (Helianthella quinquenervis). Using long‐term demographic data for three populations that span the species’ elevation range (8–15 years, depending on the population), we first examine how snowmelt date affects plant vital rates. To verify vital rate responses to snowmelt date experimentally, we manipulate snowmelt date with a snow removal experiment at one population. Finally, we construct stochastic population projection models and Life Table Response Experiments for each population.

   We find that populations decline (λ_s < 1) as snowmelt dates become earlier. Frost damage to flower buds, a consequence of climate change‐induced earlier flowering, does not contribute strongly to population declines. Instead, we find evidence that negative effects on survival, likely due to increased drought risk during longer growing seasons, drive projected population declines under earlier snowmelt dates.

   Synthesis.Shifts in flowering phenology are a conspicuous and important aspect of biological responses to climate change, but here we show that the phenology of reproductive events can be unreliable measures of threats to population persistence, even when earlier flowering is associated with substantial reproductive losses. Evidence for shifts in reproductive phenology, along with scarcer evidence that these shifts actually influence reproductive success, are valuable but can paint an incomplete and even misleading picture of plant population responses to climate change.

    

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3. Out of the temperate zone: A phylogenomic test of the biogeographical conservatism hypothesis in a contrarian clade of ants

   https://doi.org/10.1111/jbi.14462  

   Branstetter, Michael G. ; Longino, John T. ; Reyes‐López, Joaquín L. ; Brady, Seán G. ; Schultz, Ted R. ( July 2022 , Journal of Biogeography)

   The standard latitudinal diversity gradient (LDG), in which species richness decreases from equator to pole, is a pervasive pattern observed in most organisms. Some lineages, however, exhibit inverse LDGs. Seemingly problematic, documenting and studying contrarian groups can advance understanding of LDGs generally. Here, we identify one such contrarian clade and use a historical approach to evaluate alternative hypotheses that might explain the group's atypical diversity pattern. We focus on the biogeographical conservatism hypothesis (BCH) and the diversification rate hypothesis (DRH).

   Global.

   Ants (Hymenoptera: Formicidae: Stenammini).

   We examined the shape of the LDG in Stenammini by plotting latitudinal midpoints for all extant, described species. We inferred a robust genome‐scale phylogeny using UCE data. We estimated divergence dates using beast2 and tested several biogeographical models inBioGeoBEARS. To examine diversification rates and test for a correlation between rate and latitude, we used the programs BAMM and STRAPP, respectively.

   Stenammini has a skewed inverse LDG with a richness peak in the northern temperate zone. Phylogenomic analyses revealed five major clades and several instances of non‐monophyly among genera (Goniomma,Aphaenogaster). Stenammini and all its major lineages arose in the northern temperate zone. The tribe originated ~51 Ma during a climatic optimum and then diversified and dispersed southward as global climate cooled. Stenammini invaded the tropics at least seven times, but these events occurred more recently and were not linked with increased diversification. There is evidence for a diversification rate increase in HolarcticAphaenogaster + Messor, but we found no significant correlation between latitude and diversification rate generally.

   Our results largely support the BCH as an explanation for the inverse latitudinal gradient in Stenammini. The clade originated in the Holarctic and likely became more diverse there due to center‐of‐origin, time‐for‐speciation and niche conservatism effects, rather than latitudinal differences in diversification rate.

    

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4. Isotopic niche partitioning in two sympatric howler monkey species

   https://doi.org/10.1002/ajpa.24028  

   Flores‐Escobar, Elizabeth ; Sanpera, Carolina ; Jover, Lluís ; Cortés‐Ortiz, Liliana ; Rangel‐Negrín, Ariadna ; Canales‐Espinosa, Domingo ; Dias, Pedro Américo D. ( February 2020 , American Journal of Physical Anthropology)

   Ecological similarity between species can lead to interspecific trophic competition. However, when ecologically similar species coexist, they may differ in foraging strategies and habitat use, which can lead to niche partitioning. As the body tissues of consumers contain a stable isotope signature that reflects the isotopic composition of their diet, stable isotope analysis is a useful tool to study feeding behavior. We measured the isotopic niche width, which is a proxy for trophic niche width, of mantled (Alouatta palliata) and black (A. pigra) howler monkeys. Specifically, studied populations in allopatry and sympatry to assess whether these species showed niche partitioning.

   Between 2008 and 2012, we collected hair samples from 200 subjects (113 black and 87 mantled howler monkeys) and used continuous flow isotope ratio mass spectrometry to estimateδ¹³C andδ¹⁵N. We described the isotopic niche width of each species in allopatry and sympatry with the Bayesian estimation of the standard ellipse areas.

   In allopatry, isotopic niche width and isotopic variation were similar in both species. In sympatry, black howler monkeys had a significantly broader isotopic niche, which was mainly determined by highδ¹⁵N values, and included the majority of mantled howler monkeys' isotopic niche. The isotopic niche of mantled howler monkeys did not differ between sympatry and allopatry.

   The coexistence of these ecologically similar species may be linked to trophic niche adjustments by one species, although the particular features of such adjustments (e.g., dietary, spatial, or sensory partitioning) remain to be addressed.

    

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5. Differences in style length confer prezygotic isolation between two dioecious species of Silene in sympatry

   https://doi.org/10.1002/ece3.1350  

   Nista, Phil ; Brothers, Amanda N. ; Delph, Lynda F. ( June 2015 , Ecology and Evolution)

   One fundamental signature of reinforcement is elevated prezygotic reproductive isolation between related species in sympatry relative to allopatry. However, this alone is inadequate evidence for reinforcement, as traits conferring reproductive isolation can occur as a by‐product of other forces. We conducted crosses betweenSilene latifoliaandS. diclinis, two closely related dioecious flowering plant species. Crosses withS. latifoliamothers from sympatry exhibited lower seed set than mothers from five allopatric populations whenS. dicliniswas the father. However, two other allopatric populations also exhibited low seed set. A significant interaction between style length and sire species revealed that seed set declined as style length increased when interspecific, but not intraspecific, fathers where used. Moreover, by varying the distance pollen tubes had to traverse, we found interspecific pollen placement close to the ovary resulted in seed set in both long‐ and short‐styledS. latifoliamothers. Our results reveal that the long styles ofS. latifoliain sympatry withS. dicliniscontribute to the prevention of hybrid formation. We argue that forces other than reinforcing selection are likely to be responsible for the differences in style length seen in sympatry.

    

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