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Transposable elements are one of the major contributors to genome-size differences in metazoans. Despite this, relatively little is known about the evolutionary patterns of element expansions and the element families involved. Here we report a broad genomic sampling within the genus Hydra, a freshwater cnidarian at the focal point of diverse research in regeneration, symbiosis, biogeography, and aging. We find that the genome of Hydra is the result of an expansion event involving long interspersed nuclear elements and in particular a single family of the chicken repeat 1 (CR1) class. This expansion is unique to a subgroup of the genus Hydra, the brown hydras, and is absent in the green hydra, which has a repeat landscape similar to that of other cnidarians. These features of the genome make Hydra attractive for studies of transposon-driven genome expansions and speciation.

Executive Summary: The International Organization of Migration has characterized the US-Mexico border as the world's deadliest land migration route. By August 2024, a minimum of 5,405 persons had died or gone missing along this border since 2014, with record high numbers since 2021. Migrant deaths occur despite decades of: US Border Patrol search and rescue initiatives; public education campaigns targeting potential migrants on the dangers of irregular migration; dozens of academic publications and reports highlighting the root causes of these deaths; efforts by consular officials, local communities, and humanitarian agencies to locate, identify, and repatriate human remains; and desperate attempts by families to learn the fate of their missing loved ones. This paper introduces a special edition of the Journal on Migration and Human Security (JMHS), which draws on original research and the expertise of medical examiners, forensic anthropologists, social scientists, and humanitarian organizations to examine this persistent human tragedy. Many of the authors investigate migrant deaths in their professional capacities. They identify the dead, return remains to family members, and champion reforms to prevent deaths and better account for the dead and missing. This JMHS special edition represents a collaboration between the University of Arizona's Binational Migration Institute, the Center for Migration Studies of New York (CMSNY), and the Working Group on Mapping Migrant Deaths along the US Southwest Border. The Working Group includes scholars and practitioners from California, Arizona, New Mexico, Texas, and New York who have met monthly since October of 2021. The special edition examines in granular detail the causes of migrant deaths, US border enforcement strategies and tactics, migrant death statistics, and the resource and capacity challenges faced by US counties along and leading from the US-Mexico border in investigating these deaths. The US Department of Homeland Security (DHS) and many public officials attribute the deaths to the predations of human smugglers, the victims' ignorance or assumption of risk, and the harsh "natural" conditions to which migrants finally succumb. This special issue also documents the underlying non-natural causes of this enduring tragedy, and offers both overarching and more targeted solutions to preventing and minimizing migrant deaths. The issue builds upon and extends seminal research on migrant deaths first featured in CMSNY publications more than two decades ago. Section I introduces the issue of migrant deaths by posing the question: Why should we care? Section II describes the genesis of "prevention through deterrence"—a border enforcement theory and strategy—and its evolution through subsequent Customs and Border Protection (CBP) and US Border Patrol strategic plans. It describes the immense enforcement infrastructure built around this idea by successive administrations and Congresses, and it explains why it has failed to stem irregular migration and how it has contributed to migrant deaths. Section III reviews the main causes of migrant deaths—forced migration, the combined effects of prevention through deterrence and border enforcement tactics, the denial of access to asylum, the border wall, the "naturalization" of migrant deaths, and the dominant vision of the border as a site of danger and exclusion. Section IV reviews the legislative standards for identifying, investigating, and reporting on migrant decedents. It also details the deficiencies of Border Patrol and county-level sources of data on deaths, and it outlines ways to strengthen data collection. Section V discusses the burdens placed on communities along and leading from the border in investigating deaths and their need for greater resources and capacity to address this problem. Section VI outlines the anomalies and challenges related to the Border Patrol's migrant rescue program. Section VII describes international legal standards to guide the investigation of migrant deaths and two model programs. Section VIII sets forth policy recommendations to prevent migrant deaths and to honor and account for the dead. [ABSTRACT FROM AUTHOR]

Executive Summary: Immigration at the US-México border has drastically changed since the mid-2010s. Instead of adult undocumented Mexican men, generally migrating for economic purposes, there are now large numbers of men, women, unaccompanied minors, and families from diverse countries seeking asylum in the United States, as they are allowed to do under US and international law. In response to these changes, the US federal government leveraged multiple strategies to impede access to the country's asylum system, including relying on Title 42 "expulsions." Title 42, a COVID-19-era health measure, prevented migrants from initiating an asylum claim. Instead, asylum-seekers were typically immediately expelled to the closest port of entry in México. The use of public health as a pretext to control the border placed these migrants at risk and led many to attempt repeat border crossings. Given this policy context, we ask: what, if any, is the association between Title 42 expulsions and migrant deaths in southern Arizona? We address this question by drawing on records of recovered undocumented border crosser (UBC) remains investigated by the Pima County Office of the Medical Examiner (PCOME) in Tucson, Arizona. We examined differences in the number and demographic characteristics of UBC remains recovered between what prior studies have characterized as the "Localized Funnel Effect" Era of border enforcement in southern Arizona (i.e., October 1, 2013–March 19, 2020; N = 851), and the "Title 42" Era (i.e., March 20, 2021–September 30, 2023; N = 709). We also assessed how, if at all, the geography of recovered UBC remains shifted between these eras. We found that migrant deaths rose from an annual mean of 133 during the Localized Funnel Effect (LFE) Era to 198 in the Title 42 (T42) Era, representing a 48 percent increase. Compared to the earlier era, remains recovered during the T42 Era clustered closer to the border and near the cities of Nogales and Agua Prieta, Sonora, having shifted from west to east in southern Arizona. Additionally, we found that Title 42 disproportionately affected Mexican and Guatemalan nationals both in terms of expulsions as well as deaths. We propose several policy recommendations based on our study's findings intended to reduce unnecessary suffering and increase human security: • The US federal government should not impede or limit migrants' access to the asylum system. Policymakers should instead create clear pathways and procedures that obviate the need for migrants to undertake dangerous journeys and overcome barriers to fair consideration of their claims. • The US government must expand its ability to address these claims, as continued attempts to block asylum seekers will result in additional loss of life and increased violence. It should increase its capacity to screen asylum seekers at the US-México border. We propose an increase in USCIS Asylum Officers to carry out this duty. US Customs and Border Protection agents should not screen asylum seekers, nor should they assume the responsibility of serving as asylum officers, given the agency's extensively documented record of persistently dehumanizing and mistreating migrants. • The US federal government must take measures to eliminate the backlog of asylum cases in the immigration courts. These measures need to include reforms in the underlying immigration system and in the removal adjudication system, such as greater access to legal counsel and changes to the law that offer legal pathways to imperiled migrants who do not meet the narrow definition of asylum. Absent these reforms, the asylum case backlog will grow, and many asylum seekers with strong claims to remain will be removed after living for years in the United States. [ABSTRACT FROM AUTHOR]