J. Jaime Zúñiga-Vega’s research while affiliated with National Autonomous University of Mexico and other places

Hummingbirds play an important role as pollinators and are one of the primary examples of animal–plant coevolution. However, factors such as land‐use change, urbanization, exotic species introductions and the disappearance of native plants can negatively affect the persistence of hummingbird populations. Thus, understanding the ecological factors that may favour their presence is essential for their effective conservation in urban areas. We conducted repeated surveys in a native scrubland reserve within Mexico City from 2015 to 2018, and used conditional two‐species occupancy models to estimate a species interaction factor, and to analyse the effect of five native plants ( Agave salmiana , Echeveria gibbiflora , Opuntia lasiacantha , O. tomentosa and Wigandia urens ) and one exotic plant ( Leonotis nepetifolia ) on the occupancy probability of two hummingbirds: the Broad‐billed Hummingbird ( Cynanthus latirostris ) and the Berylline Hummingbird ( Saucerottia beryllina ). Considering that both of the hummingbird species could be competing for similar resources, we also tested the effect of the presence of the Berylline Hummingbird on the occupancy of the Broad‐billed Hummingbird, assuming its dominance based on larger body‐size. We found evidence of positive spatial interactions between plants and hummingbirds, but we did not find these to be consistent throughout the 3 years of monitoring, which could indicate a modification of the original hummingbird–plant interaction networks resulting from urban disturbance. In addition, there were no negative spatial interactions between the two hummingbirds. Instead, we detected an aggregation of both species during two separate seasons, probably owing to one species using the other as a cue for profitable sites. Even though the populations of these two hummingbird species can thrive in an urban ecosystem, changes in spatial interactions might reflect alterations on the structure and functioning of a community. Therefore, we consider it crucial to continue studying their population dynamics and their implications for the conservation of urban hummingbirds.

The distribution patterns of species can be impacted by biotic and abiotic factors that occur at both macro- and microscales. At a macroscale, species distributions can be impacted by spatiotemporal factors limiting dispersal and source–sink metapopulation dynamics that contribute to shaping geographic ranges. At a microscale, species distributions can be impacted by resources, microclimate, and interactions with other taxa. Thus, studying species at a single scale, or even at a single location, limits our understanding of the habitat needs and preferences. Herein, we study a lizard species, Sceloporus tristichus, that has a geographically diverse distribution, to understand the species' habitat needs and preferences at both macro- and microscales. We used species-occupancy models to identify habitat characteristics that are essential to predicting the presence of S. tristichus. In addition, we sampled various locations to understand the microhabitat preferences of the species. Last, we conducted a validation test to determine how well our model performed by choosing and sampling additional sites guided by the occupancy modeling results: two sites presumed to have the species and two presumed not to have the species. We found that the occupancy probability of S. tristichus lizards positively correlated with tree cover, tree height, and elevation. The detection probability of the species positively correlated with relative humidity. We also found that the species was using perches that were closer to the ground and cooler than what was available in that habitat. Our validation test verified our findings. Our results emphasize the need for old succession forests and particular tree species that are found at high elevations for S. tristichus occupancy. Herein, we have shown the importance of studying a species at different ecological scales to gain a holistic understanding of the species' ecological needs and preferences that can help in both comparisons with other congeners and conservation efforts.

The Jalisco mud turtle Kinosternon chimalhuaca is an endemic species from the Pacific coast of Jalisco and Colima states, Mexico. The species has been poorly studied and much of its natural history and ecology are unknown. We analysed the demography and basic reproductive ecology of a population inhabiting a canal in a peri-urban area on the coast of Jalisco, Mexico. We use a mark-capture-recapture dataset collected over four years (2019–2022) to perform multi-state and time-symmetric open models (Pradel) to calculate population growth, recapture and transition probabilities. A total of 530 turtles were captured and marked during the study. Survival probability was higher in adults compared to juveniles. The estimated abundance of the population studied was between 699 and 778 turtles, with a sex ratio biased toward females. Using radiographs, we found that clutch size was 3.89 (± 0.81) eggs, with a range from 3 to 6 eggs, we also found evidence of pelvic constraint on egg size. The studied population is restricted to subsidised man-made canals and was considered stable. The information generated in this paper will be useful for the much needED conservation assessments of mud turtles. Keywords: abundance, survivorship, recapture probability, reproduction, pelvic constraint, subsidised population

The evolution of placentation is predicted to intensify intergenomic conflicts between mothers and offspring over optimal levels of maternal investment by providing offspring opportunities to manipulate mothers into allocating more resources. Parent-offspring conflicts can result in the evolution of reproductive isolation among populations when conflicts resolve in different ways. Postzygotic reproductive isolation is hypothesized to evolve more rapidly following the evolution of placentation due to the predicted increase in conflict. We tested this hypothesis by performing interpopulation crosses within placental and non-placental species of Poeciliopsis to determine if the relationship between genetic distance and measures of postzygotic reproductive success differed as function of reproductive mode. We did not observe any differences in offspring viability or sterility among crosses. Offspring size declined rapidly as a function of interpopulation genetic distance within the placental species, but not among our non-placental species. The decrease in offspring size in the placental species was beyond normal variation, likely representing a major fitness cost, consistent with the prediction that negative epistatic interactions are evolving more quickly among populations in our placental species than the non-placental species. We discuss how our results support the role parent-offspring conflicts play in the evolution of reproductive isolation and reproductive mode.

This study explores how specific reproductive strategies, placentotrophy and superfetation, influence the evolution of male gonopodial structures in livebearing fishes of the family Poeciliidae. Although previous expectations pointed to higher diversification rates in species exhibiting both placentotrophy and superfetation, our results offer an alternative perspective. Species lacking both placentotrophy and superfetation displayed elevated rates of diversification in gonopodium depth and length. Furthermore, species in which males exhibit colourful ornaments and/or courtship behaviour also had greater diversification rates of gonopodial length in comparison to species that lack these male traits. In addition, the evolution of gonopodial length was influenced by the presence of superfetation, with species exhibiting this reproductive strategy evolving towards longer gonopodia (regardless of the presence or absence of placentotrophy). Likewise, the optimal number of serrae on the gonopodia was significantly higher in species with superfetation, indicating their role in ensuring copulatory success in the face of increased male–male competition. In conclusion, although the expected link between gonopodial diversification and the joint presence of placentotrophy and superfetation was not fully substantiated, our study indicates that superfetation and the presence of male traits associated with precopulatory sexual selection have had a substantial influence on the evolution of gonopodial structures.

Life history theory predicts that a trade‐off may occur when an increased investment in one fitness component causes a reduced investment in another. Parasites generate changes in the optimal life history traits of organisms, causing compromises for their hosts. The objective of this research was to determine whether trematodes Clinostomum sp. and Uvulifer sp. inflict measurable damage on the males of the viviparous fish Poeciliopsis infans , generating trade‐offs between somatic condition and reproductive traits (gonad mass and gonopodium length). We found (i) a negative relationship of large encysted metacercariae and non‐encysted metacercariae on somatic condition. Interestingly, individuals with a higher parasite load had a worse body condition, but bigger gonads and longer gonopodium; and, (ii) a bond between small encysted metacercariae and non‐encysted metacercariae with smaller gonopodia, only in fish with poorer somatic condition. The strongest correlation was given by the non‐encysted metacercariae, probably due to mechanical damage during migration through the body cavity. We did not find any trade‐off effects of Uvulifer sp. We consider that the statistical effects found on somatic condition can be attributed to a greater reproductive investment, generating energetic costs that compromise their defences against infection, allowing a greater parasite load.

Urban growth often leads to land-use changes that result in biodiversity loss and reduced human benefits. In urban zones, green areas facilitate physicochemical processes (such as carbon capture, reducing environmental temperature and noise pollution), offer multiple benefits to human beings (e.g., water filtration and purification), and support numerous vertebrate populations, including birds. In the tropics, the capacity of green spaces to maintain bird populations is regulated by characteristics of these areas (e.g., vegetation structure) and environmental seasonality. In order to generate ecological knowledge to help conserve bird diversity in large urban settlements, this study aimed to (1) identify the most influential variables on the distribution of bird species in green areas of a tropical megacity, and (2) assess how bird richness varies between the dry and rainy seasons. Across two dry and rainy seasons between 2021 and 2022, detection records of 108 bird species were obtained from 101 green areas. Air temperature and sampling time were the primary factors influencing bird detection. Bird occupancy and richness were higher in parks near other green areas in first dry and increased with tree richness during the rainy seasons. Floral abundance explained the occupancy and richness in the second dry season. In 2021, the highest richness was observed during the dry season, while in 2022, the highest richness was estimated during the rainy season. These findings highlight the importance of resource availability and spatial arrangement in urban green areas for bird diversity, offering insights for conservation and maintaining ecosystem benefits in urban environments.

Urbanization has forced animals to respond to novel environments. One of the basic questions in urban ecology is if ecological processes that occur in natural conditions also occur in urban environments. In natural ecosystems, key predators can limit prey abundance and have a widespread effect on trophic levels. Here, we examine a predator-prey interaction in Mexico City, an urban ecosystem where prey can be evaluated in the presence or absence of apex predators. Nearly all original ecosystems in Mexico City have been transformed for human purposes. Many of the green spaces in the city contain populations of the Mexican gray squirrel, a species native to this area. These green spaces are also inhabited by different species of raptors, the most frequent being Harris's hawk, Cooper's hawk, and sharp-shinned hawk. Little is known about the interactions between raptors and squirrels, particularly how different environmental factors influence this ecological relationship. We do know, however, that raptors prey on squirrels. We predicted that in parks where raptors were present, there would be fewer squirrels than in parks where there were no raptors. We studied the relationship between raptors and squirrels using occupancy models, which also allowed us to evaluate environmental factors that affect the presence of both squirrels and raptors. We also tested if the presence of raptors influenced the occupancy probability of squirrels, and vice versa. Lastly, we estimated the abundance of squirrels in parks, both where raptors were present and where they were absent. Contrary to our predictions, in our first two sampling periods we found a positive relationship between the presence of raptors and squirrel abundance, but this relationship was absent during our second two survey periods, which was due to a decline in squirrel abundance in parks where raptors were present. These results suggest that predator-prey interactions occur in urban settings much as they do under natural conditions, but that other factors unique to urbanization can also impact the abundance of raptors and squirrels. Our findings also suggest that raptors might be an effective means of controlling squirrel populations under some conditions.